How To Install a TR3550 Tremec Transmission Into a Dentside Ford

Improving Shift Feel With A TR3550 transmission in a 1976 Ford F-100

By Don Lindfors – Photography by the Author

When we think of Classic Truck Performance the first thing that comes to mind is the engine. These days that usually seems to involve 5.0 Coyote or LS swaps. Other performance enhancements center around suspension or complete aftermarket chassis upgrades and bigger brakes. Transmissions seem to be forgotten in many cases unless an entire modern drivetrain is being transplanted.

01 time to start removing the old shifter assembly on this F100
First step was to peel back the crumbling rubber mat, remove the cracked rubber boot, and unscrew the giant nut holding the shifter to the trans.
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When our classic trucks were new, they were designed as work vehicles and as such engine and transmission choices were geared toward that end. Automatics weren’t all that common and in the case of GM, offerings were originally the two-speed powerglide transmission, later replaced by the Turbo 350 and Turbo 400. Fords were blessed with three-speed auto, but none of these transmissions, and the accompanying rear end gear ratios, were designed for the way we use classic trucks today. As personal transportation, performance vehicles, and weekend cruisers, these old gearing options don’t cut it with today’s faster speeds that seem to be the norm. On the manual transmission side, things weren’t much better with three- and four-speed “truck” transmissions. Heavy gears and slow shifting do not make for a lot of fun when driving a three-pedal truck for pleasure.

Read More: The Perfect C10 Combo!

02 We remove the transmission floor cover to allow easy access to the transmission
Next, we removed the transmission floor cover to allow easy access to the trans and wiring.

Our project 1976 F-100 was ordered as a farm truck where it spent most of its life. It had an unusual combination of a 302 small block Ford with a four-speed BorgWarner T18 transmission, popularly called the “Granny Low” transmission. First gear is an absurdly low 6.32:1 ratio, good for crawling up the side of a mountain with a heavy load. It also means you go about 10 feet before needing to shift the big gap to Second. When put behind Ford big block engines or the mighty 460, most owners just choose to use the torque and start off in Second gear, but that isn’t really an option with the 302 engine. Something had to change to make this old truck more enjoyable.

03 Remember to unplugged the Speedo Drive Wiring and the Back Up Light Switch Plug on this Dentside Ford
Before going underneath, we unplugged the Speedo Drive Wiring and the Back Up Light Switch Plug. That trans showed 45 years of grease and grime.
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We thought about doing a late-model engine and transmission swap but we really like the 302 Ford engines and want to keep this truck a budget build. Not everyone is ready to drop $10,000-15,000 (or more) on a Coyote swap. We thought about doing a four-speed AOD automatic transmission, but there is something about the fun of rowing your own gears that still appeals to us. So, we decided to look at modern manual transmission options.

04 the clutch linkage above the new header need to be removed
All the clutch linkage above the new header (more about that later) needs to be removed; we won’t be using it.

TREMEC has become the leader in aftermarket performance transmissions as well as the builder for many OEM manual gearboxes. Although we would have loved to just order up a new five-speed TKX transmission  or six-speed T56 Magnum transmission and an installation kit, you will drop a good $5,000 or more to go this way. Keeping with our budget theme, we decided to see what was available. We did some forum watching and found a TREMEC TR3550 five-speed that a fellow was taking out of his Falcon to get the latest six-speed. The TR3550 is the basis for the TKO 500 and 600 and is perfect for our projected power output.

Read More: No-Holds-Barred 1956 F100

05 The factory Dentside Ford transmission starter bolts need to be replaced
The starter bolts to the bellhousing so it needs to be removed.

This transmission is somewhat unique, having only come in one car as an OEM offering, the 1995 Mustang Cobra R. But it was also offered as an aftermarket offering until 2004 when the TKO 500/600 were introduced. We talked to the Falcon guy and made a deal to purchase his TR3550 and he included a new clutch, throw-out bearing, and the driveshaft with the proper yoke. We opened the transmission and it was like new, and the oil was clean and clear. To install this in our 1976 F-100 we needed a bellhousing and a way to connect the clutch to the truck. We probably could have made the original Z Bar mechanical linkage work with some fiddling around but figured there was a better way. We talked to Bruce Couture at Modern DriveLine and found out there was. Modern DriveLine has been at the forefront of the Ford five- and six-speed transmission conversion business for over 20 years and a TREMEC Elite distributor since 2008. They were the innovators in cable clutch conversion kits for early Mustangs and T5 transmission installation kits and now offer complete kits for not only Fords, but also GM, Mopar, and even AMC vehicles. They are also a leader in hydraulic clutch conversions with thoroughly engineered kits. For our F-100 they offer a simple cable conversion using the stock clutch pedal and connecting to the TREMEC clutch fork. They have hydraulic conversions for earlier F-100s and are working on them for the 1973-78 trucks as well. Our conversation with Couture also shed some light on the shifter position of our new transmission. The original Granny low shifter was a massive affair that started very far forward, basically under the dash. The new transmission shifter would be right against the seat and might work with a forward leaning shifter but would keep my wife from driving as the seat couldn’t slide forward. Modern DriveLine had a solution in a Tremec Mid-Shift kit that would move the shifter forward about 7 inches, a perfect location. So, we ordered up the Cable Clutch kit, a new OEM-type bellhousing with clutch fork, the Tremec Mid-Shift kit, and the necessary hardware. We decided to splurge a little and get a fancy Billet Shifter from Lokar Performance Products, along with one of their high-quality shifter boot kits. We also needed a new 153T flywheel (the T18 transmission used a 164T) and went with a Ford Performance SFI billet flywheel and a set of ARP flywheel bolts to hold it all together.

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06 The speedo sensor for the Dakota Digital gauges need to be removed
The electronic speedo sensor for the Dakota Digital gauges that we installed in the Nov. ’21 Classic Truck Performance issue unbolts; this would be the cable on stock trucks.

The installation was quite straight forward as you’ll see in the photos and captions. We were able to use the original transmission crossmember by moving it rearward and drilling two new mounting holes. The yoke that we got with the transmission was the same U-joint size as our truck driveshaft, so we installed it with a couple of new U-joints. The driveshaft was an inch too long, so a local driveshaft shop shortened it and gave it a new balance job overnight.

07 The Dentside Ford crossmember needs to come out
There are two crossmember that need to come out for transmission removal; the rear one that supports the transmission mount and this forward one that ties the suspension radius arm mounts together.

Now that we are driving the truck again it is amazing how much this swap transformed the truck, making it much more fun to drive. No more shifting out of First before passing the crosswalk or slipping the clutch to start in Second. The shifts are nice and crisp and the 0.68 Overdrive not only lowered the revs by about 900 rpm at 70 mph, resulting in noticeably better gas mileage, but it’s much quieter in the cab as well. All said and done we spent about half the cost of doing a new kit and if we do have any issues down the road, Modern DriveLine has the parts and expertise to rebuild the TREMEC line of transmissions as well. If you’re running a classic truck and want to improve performance while staying with the original-style engine, a transmission swap should be on your short list.

08 Use a transmission jack to make the removal on the F100 easier
Using a transmission jack will make the job easier and safer. After placing the jack in place we removed the trans to bellhousing bolts and …
09 Now carefully lower the transmission out of the F100
… slid the trans back and lowered it out of the truck.
10 With the transmission out of the way, the bellhousing was removed next
With the transmission out of the way, the bellhousing was removed next.
11 T18 transmission vs. TR3550 transmission
Here is a side-by-side comparison between the T18 four-speed and the TR3550 five-speed that is going in. For fun I decided to weigh them both. With the bellhousing, clutch, flywheel, and transmission the T-18 came in at a hefty 285 pounds! Now you can see why we used a transmission jack. With the same parts the five-speed weighed in at 175 pounds, a reduction of 110 pounds.
12 Here_s a look at the rebuilt engine in the Dentside Ford
When I bought this truck, I had a feeling the engine had been rebuilt. Once the flywheel and starter plate were out of the way it was obvious it had been; always good news.
13 We used a Modern Driveline starter plate to match up the transmission
Due to the smaller-diameter flywheel and bellhousing, the starter plate had to be replaced to match. Modern DriveLine had the right one in stock.
14 Here is the Ford Performance flywheel we used with the correct 153 tooth count
Since the five-speed requires a smaller 153-tooth flywheel (versus the truck 164T) we picked up this billet one from Ford Performance Parts. SFI rated, we know it isn’t going to come apart on us should we put a bunch of power to it in the future.
15 we utilized arp bolts to secure the flywheel in place
To make sure it stays in place we always use new flywheel bolts, and ARP is the standard of the industry for the highest quality.
16 remember to apply assembly lube on the flywheel bolts
ARP includes this special lube that goes both on the threads and under the head to guarantee the proper torque rate is achieved.
17 Its always a good idea to chase threads on the crankshaft
It’s always a good idea to chase the threads in the crank. We almost skipped this step, getting ahead of ourselves, but when starting some bolts by hand we noticed they felt tight. Sure enough, the old bolts had been installed with Loctite and material was left behind. Out came the thread chase tap and we chased all the boltholes and then blew them out with air before …
18 Time to torque the flywheel to spec on our 302 engine
… torquing them in three steps, in a crisscross pattern, to the final torque of 75 lb-ft.
19 The Ford performance flywheel gets installed next
Next came the Ford Performance Diaphragm clutch that we got with the trans.
20 Modern DriveLine supplied the new bellhousing and throw-out fork to mate the TR-3550 to out 302
Modern DriveLine supplied the new bellhousing and throw-out fork to mate the TR-3550 to out 302.
21 Modern DriveLine also has all the proper hardware to install the bellhousing and the transmission
Modern DriveLine also has all the proper hardware to install the bellhousing and the transmission, so that saved us rooting around our hardware box for suitable bolts or ending up with inferior-quality hardware store stuff.
22 We put a little bit of Lucas Extreme Pressure grease on the Ball Stud in the bellhousing
We put a little bit of Lucas Extreme Pressure grease on the Ball Stud in the bellhousing and then …
23 Next we installed the throw-out bearing fork before installing the bellhousing to the motor
… installed the throw-out bearing fork before installing the bellhousing to the motor.
24 The TR3550 was set up for the Mustang Cobra that it came from, so the shifter was all the way to the rear of the transmission
The TR3550 was set up for the Mustang Cobra that it came from, so the shifter was all the way to the rear of the transmission—not ideal for a truck installation.
25 To solve that problem, Modern DriveLine manufactures this billet mid-shifter conversion kit
To solve that problem, Modern DriveLine manufactures this billet mid-shifter conversion kit. They offer many different styles for other TREMEC transmissions as well.
26 To install the tremec mid-shifter you need to remove the rear mount shifter and the mid cover
To install the tremec mid-shifter you need to remove the rear mount shifter and the mid cover, exposing the shifting rods and the shift lugs that need to be changed.
27 The outer shift lugs need to be removed to access the center lug that gets replaced for the mid shifter
The outer shift lugs need to be removed to access the center lug that gets replaced for the mid shifter.
28 The new center lug and the original outer two are reinstalled
The new center lug and the original outer two are reinstalled. You can see the difference when compared to photo 27.
29 The new Modern DriveLine tremec mid shifter then slips in place and bolts in with the original hardware
The new Modern DriveLine tremec mid shifter then slips in place and bolts in with the original hardware.
30 Here is the shifter of the Modern Driveline compared to the oem placement
I put the stock shifter back in place to illustrate the difference in position between the two shifters, a 7-inch forward movement.
31 With the supplied cover plate over the old shifter hole, the transmission went up on the jack and into the truck
With the supplied cover plate over the old shifter hole, the transmission went up on the jack and into the truck. So much easier with the lighter trans.
32 The rear crossmember went back in place on the Dentside Ford
The rear crossmember went back in place. We replaced the old-style, single-bolt trans mount with the newer and more-common two-stud style. We just had to drill two holes in the crossmember to accommodate.
33 The five-speed transmission mount is about 2 inches further rearward than the old four-speed
The five-speed transmission mount is about 2 inches further rearward than the old four-speed, so we had to drill two holes in the frame to bolt the crossmember in.
34 The TR3550 transmission now has a factory fitment
From the interior, the five-speed looks like it should have been there all along.
35 We decided to upgrade our starter with one from PerTronix
We decided to update the starter at the same time. PerTronix has this slick-looking line of “Contour” High Torque modern starters that can be clocked in different positions to clear headers, big bellhousings, and so on, which was perfect for our application. They offer them in polished aluminum or this shiny black powdercoat.
36 we got a new set of silver ceramic-coated headers from Patriot Exhaust Products
The headers in our truck were 40 years old and rusty, so we got a new set of silver ceramic-coated headers from Patriot Exhaust Products.
37 Patriot recently started offering these multi-layer aluminum header gaskets known as Seal-4-Good
Patriot recently started offering these multi-layer aluminum header gaskets known as Seal-4-Good. Since we hate leaky header gaskets, we decided to use them with the new headers.
38 With the new header in place we were able to clock the starter and install it with no clearance issues
With the new header in place we were able to clock the starter and install it with no clearance issues.
39 To control the clutch in the new transmission, Modern DriveLine makes this well-engineered cable conversion
To control the clutch in the new transmission, Modern DriveLine makes this well-engineered cable conversion that does away with the original rods, brackets, levers, and other complications.
40 You may have to drill holes for the clutch cable brackets like this 76 F-100
Depending on the year of your truck, you may have to drill one hole in the firewall for the clutch cable bracket like we did on this 1976. Early trucks have an existing bolt that will mount the bracket.
41 The cable mounts through the bracket and the heim joint end bolts to the pedal
After mounting the bracket, the cable mounts through the bracket and the heim joint end bolts to the pedal in the same hole the push rod was in from the factory.
42 The cable comes through the floor in the same hole as the push rod
The cable comes through the floor in the same hole as the push rod and then loops forward around the motor mount before attaching to the throw-out fork on the transmission. It comes with this heat shield installed to protect the cable.
43 With everything bolted up we filled the transmission with Lucas Sure Shift fluid
With everything bolted up we filled the transmission with Lucas Sure Shift fluid. These late-model transmissions use ATF-type fluid and TREMEC recommends GM Synchromesh fluid, and this Lucas Fluid meets those specs.
44 We called up Lokar Performance Products and ordered a 10-inch billet aluminum lever in black
As seen in the last photo, the Mustang shift lever was a bit short for the truck. We called up Lokar Performance Products and ordered a 10-inch billet aluminum lever in black and to finish off the installation on one of their Shifter Boot Kits. Modern DriveLine also offers an array of shifter levers.
45 We made a custom floor cover and a Lokar Shifter _ Boot in place to cover up the conversion
We made a small panel to cover the original shifter location and with the floor cover and the Lokar Shifter & Boot in place, we wrapped up the conversion. It looks sportier and drives like a much more modern truck–better shifts with closer ratios and the Overdrive Fifth added fuel mileage.

Sources
Modern DriveLine
(208) 453-9800
moderndriveline.com

Patriot Exhaust
(909) 599-5955
pertronixbrands.com/pages/patriot-headers

PerTronix Starters
(909) 599-5955
pertronixbrands.com/pages/pertronix-ignition-starters

Lokar Performance Products
(877) 469-7440
lokar.com

Lucas Oil
(800) 342-2512
lucasoil.com

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