Using a long 15mm box wrench for leverage and a flywheel tool, we removed the torque converter bolts.

One dilemma you will have when installing a late-model trans into your early-model car is determining how to drive the speedometer. The unit in our ’83 is cable-driven, and since the 4L60E doesn’t have a provision for a cable, and we didn’t want to change to an electronic speedometer, we chose to use a manual speedometer conversion kit (PN SW41, $400) from SW Fabrication in Texas. The kit includes a new, modified tail housing, speedometer sleeve and driven gear, vehicle speed sensor (VSS), and reluctor/drive/bushing assembly. You’ll have to provide SW with the gear ratio and tire height for your vehicle so they can provide you with the correct speedometer gear

The new reluctor/drive/bushing assembly is then slid onto the shaft. We gently tightened only one of the set screws that held the assembly into place as we needed to test-fit it with the tail housing installed.

The drive gear must be located in the center of the opening in the tailhousing where the speedometer sleeve and driven gear will be mounted. You can slide the gear back and forth to get it to this position. Once eyeballed into place, we pulled the housing back off to loctite and tighten the set screws on the gear assembly.

When installing a transmission, it's critcal to ensure the torque converter is filled with fluid and properly seated in the transmission pump. . Once the converter is in the pump housing, rotate it slowly clockwise to align the splines and hub slots. You should feel two distinct “drops” of the converter into the transmission. This will tell you that it is properly seated. To double-check it, Source Interlink’s Tech Center Manager Jason Scudellari measured the depth of the converter into the transmission case. This should be no more than 1/8-inch further than the distance from the face of the block to the mounting surface on the flexplate.

With the trans still hanging freely against the trans jack, we re-connected the rigid transmission lines, speedometer cable and shift cable, and dipstick tube. The newer model transmission does not accept the converter lock-up harness. This will be handled through the stand-alone transmission computer. We’ll show you how to install that in our next issue. We then added a new polyurethane transmission mount (PN 3.1108R, $21.95) from Energy Suspension for the transmission to rest on.

Not wanting to leave anything to chance, we greased up the speedometer drive gear and installed it to make sure that it was meshing properly with the driven gear/reluctor assembly. A few revolutions of the driveshaft verified that we had it all aligned correctly. After seating the assembly into the tailhousing by hand, we fastened it with the retaining bracket.

To mount the new transmission, we used one of BMR Fabrication’s torque arm relocation crossmember kits (PN TCC017, $254.95). This crossmember incorporates a mount for the torque arm so that it no longer needs to attach to the stock aluminum transmission tailhousing. This will eliminate the chance of breaking the housing at the stock mounting points. The crossmember also gives you multiple mounting points to allow for fine-tuning of the torque arm, and launch characteristics of the car.