Just to clear some things up , OBD1.5 is basically OBD1 with a few additions like the 16 pin diagnostic connector , and pinned differently , , but with the correct OBD1.5 adapter it is scanned using OBD1 software and tuned with OBD1 software , Some 94 cars had OBD2 , but not many , only a handful , more in 95 , and across the board universally in 96 .
here is an excerpt from a 4L60E swap guide :
To put a '95 4L60E into a '94 car: No mechanical mods required. TCC Mod (stake the TCC valve)
must be performed. The trans will operate normally without TCC Mod 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. TCC Mod must be performed. The trans will operate
normally without TCC Mod but TCC lockup will not work, so highway and cruising gas mileage will suffer
and more heat will be produced in the transmission.
TCC Mod (method 1):
An additional wire must be run from the PCM connector D pin 6 to pin "U" on the trans harness for the
TCC to work. Also, the PCM must be reprogra ed with '95 transmission base code. In my opinion this
is more work than its worth due to the amount of labor involved in properly routing an additional wire
into the powertrain wiring harness.
TCC Mod (method 2):
Leave the 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, and stake it into place. That'll lock
keep the valve acted on by the PWM in the full-open position and it'll function like a '94 style lockup. No
PCM reprogra ing required. You may have to swap the '94 internal harness into '95-'96 transmission,
but I'm not sure. I reco end not swapping harnesses if you don't have to, because they will most
likely be brittle and are tricky to remove from the case without damaging the lugs on the connector.
a 97 will swap into a 96 no problem ,,,
installing in a 95 would need some wiring mods and making it work with the 95 NSS
I have not done the swap , but seems some people have ,, but it is uncommon as most people stick to the assured method of using the same year of trans to make it simple