Wow. Their website is terrible.
The Gear Vendors overdrive kit comes complete with everything needed, including great, easy to follow instructions. Budget a day to install it, assuming you don’t have to modify your fuel tank for clearance like we did.
The main controller is mounted under the hood. You can see how well marked and how simple the wiring is.
In our particular application—and certainly not a common one, we had to cut out part of the tank to get everything to fit.
This switch to engage the overdrive is mounted on the dash. You then move the overdrive in or out with a small switch on the shift lever.
While our project ramp truck drove well before we took the engine and transmission out, we were not pleased by how fast the engine had to turn at highway speeds.
While we didn’t need to drive the truck at 80 mph, it would be nice to be able to cruise at 65-70 without the feeling that you constantly needed to shift up a gear.
A final drive change is a compromise: What you gain at highway speed, you lose in acceleration. And to our knowledge, an overdrive, five-speed swap for a heavy-duty truck is difficult—if even possible—to complete.
The one thing you can do is install an overdrive unit. Like the Laycock de Normanville electric overdrives so common in British cars in the 1960s, a company called Gear Vendors has a modern, heavy-duty version of this design.
Other than cutting part of the gas tank apart and rewelding it to clear the overdrive unit, installation is pretty straight forward.
The overdrive unit bolts on the back of the transmission after making a minor modification to your transmission’s tail shaft. Wire it up, mount the control panel on your dash, and fix the switch to the shifter and you are done.
At about $3500, this is not a cheap installation, but just one drive on the highway convinced us it was worth every penny. Our ramp truck now cruises nicely down the highway.
Watch the pages of Grassroots Motorsports for the full project car series. Subscriptions start at just $10.
I believe it is a NP 435. They had it rebuilt a few months ago.
I agree the NV4500 would have been the best route, and saved a ton of money over a rebuild and a GearVendor. Better shifting trans, as well.
The transmission rebuild was cheap, like $400. Yes we had to shorten the driveshaft. I think that was about $100. I didn't have the time or truck experience to figure out what transmissions would bolt in and work correctly. I also didn't want to be pulling these big heavy transmission in and out of trucks in the junk yard. I also kind of like the old school, notchy way the truck shifts. It brings back memories of growing up in my dad's Ford dealership and delivering trucks with him. Super cool to be driving big trucks at age 16!
I had already spent a million hours on this silly truck. The Gear Vendors set up took about a day to install and has worked flawlessly since.
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