To put a ’94 4L60E into a ’95 car: Direct bolt-in; no mechanical or electrical changes required. The PCM must be reprogrammed with ’94 transmission base code to avoid setting a silent code (Check Engine Light (CEL) does not illuminate, but code stored in memory). Trans will operate normally without reprogramming. EDIT 10/20/07 - The silent code (code 83) may inhibit TCC lockup, but I have not verified this. Three potential fixes (any one will work); 1. reprogram PCM so it doesn't look for the PWM solenoid, 2. swap the '95-96 harness into the car ALONG WITH the PWM solenoid connected but leave the solenoid in the pan, 3. wire up a manual TCC lock switch by which you can lock the converter. END EDIT.

To put a ’94 4L60E into a ’96 car: The ’96 tailshaft housing and VSS must be installed on the ’94 4L60E before the trans can be bolted into the car. No other mechanical or electrical mods necessary. The PCM must be reprogrammed with ’94 transmission base code to avoid setting a silent code (Check Engine Light (CEL) does not illuminate, but code stored in memory). Trans will operate normally without reprogramming. EDIT 10/20/07 - The silent code (code 83) may inhibit TCC lockup, but I have not verified this. Three potential fixes (any one will work); 1. reprogram PCM so it doesn't look for the PWM solenoid, 2. swap the '95-96 harness into the car ALONG WITH the PWM solenoid connected but leave the solenoid in the pan, 3. wire up a manual TCC lock switch by which you can lock the converter. END EDIT.

To put a ’95 4L60E into a ’96 car: The ’96 tailshaft housing and VSS must be installed on the ’94 4L60E before the trans can be bolted into the car. Technically, the 3-2 downshift solenoid should be swapped also, but experience shows that it is not required.

To put a ’95 4L60E into a ’94 car: No mechanical mods required. Mod A must be performed. The trans will operate normally without Mod A but TCC lockup will not work, so highway and cruising gas mileage will suffer and more heat will be produced in the transmission.

To put a ’96 4L60E into a ’95 car: The ’95 tailshaft housing and VSS must be installed on the ’96 4L60E before the trans can be bolted into the car. Technically, the 3-2 downshift solenoid should be swapped also, but experience shows that it is not required. No other modifications are necessary.

To put a ’96 4L60E into a ’94 car: The ’94 tailshaft housing and VSS must be installed on the ’96 4L60E before the trans can be bolted into the car. Mod A must be performed. The trans will operate normally without Mod A but TCC lockup will not work, so highway and cruising gas mileage will suffer and more heat will be produced in the transmission.

Mod A (method 1):
An additional wire must be run from the PCM pin TBD to pin TBD on the trans harness for the TCC to work. Also, the PCM must be reprogrammed with ’95 transmission base code.

Mod A (method 2):
Swap the ’94 internal harness into '95-’96 transmission, leave PWM solenoid unplugged but installed. On the valve directly to the right of the PWM solenoid – push that valve all the way towards the outside of the valvebody , push it against the side of the valvebody and stake it into place. That’ll lock down your PWM function and it’ll function like a regular lockup. No PCM reprogramming required. Now with pics!