Unless you run into insurmountable driveshaft issues (slip yoke versus fixed yoke) your transfer case from the older truck should bolt right into the newer driveline. Then that would let your 87 speedo work and I think it would be worth the trouble.
The PSOM module takes the raw signal from the sensor in the rearend, and then modifies this signal and then sends it to the engine/tranny computer, the ABS module, the cruise control module, and anything else that needed it. A lot of unnecessary complication that you would not need in your earlier wiring harness.
The PSOM module takes the raw signal from the sensor in the rearend, and then modifies this signal and then sends it to the engine/tranny computer, the ABS module, the cruise control module, and anything else that needed it. A lot of unnecessary complication that you would not need in your earlier wiring harness.