1966 Chevy Chevelle Gear Vendor Unit Install - Split Decision

Using a zip tie as a reference, Chavez used the measurement and shortened the shaft. Then, with a cutting wheel Chavez trimmed 13/8 inches off of the shaft.

After the shaft was trimmed we could mock up the GV tailhousing for floor clearance. Normally, with the shorter TH350 space wouldn't be an issue; since the Chevelle utilized a 700-R4 with a shifter bracket located in a funky position there were some clearance issues to contend with. We used an air hammer to create more space where it was needed.

When installing the GV tailhousing, there is no guesswork on its position, as the word "TOP" is cast on the housing. Still, should you encounter any fitment issues, the transmission crossmember can be flipped 180 degrees. In this instance, the fit was a slam dunk and the GV tailhousing fit in the same location as the 700-R4's location.

The auto-drive control unit is the brains of the operation. It's an interface which can control up-shifts into a split overdrive based on speed or rpm. Each Gear Vendor unit comes with this unit and it's a cinch to install cleanly under any dash. Since the 700-R4 already has an overdrive gear (4) from the factory, Gear Vendors used their dash switch delete option. Simply put, there is no AutoDrive (automatic engagement at cruising speed of the Gear Vendors like you would want with a 3 speed automatic). Dashswitch delete still gives you AutoLaunch for the automatic application of First over at the dragstrip and turns the overdrive off (if you have forgotten to) at low speeds so you always take off in First.

Next, we installed the coupler which adapts the smaller output shaft of the 700-R4 to the larger 32-spline input shaft in the GV unit.

We used a straight edge to confirm we had the length correct (shims provided). The accuracy of this measurement will ensure the two flanges will meet together and bolt up.

We screwed in the 10-inch speedometer cable into the speed sensor on the GV unit. From there we placed the other end of the GV speedometer cable into the factory speedometer cable.

This end also contains the sensor that converts the speed info to the electronics using a VSS signal.

Since the GV unit hangs farther off the back of the transmission, a shorter driveshaft must be placed back in. Our new driveshaft was actually the original unit from the car that was cut down 1211/16 inches and balanced.

With the driveshaft installed we filled the overdrive up with 27oz of Castrol Syntorq LT (GM # 12346190). We also checked the main trans fluid level while idling in park. Finally, we could get the car back down to the ground.