I think you asked a very key question. What compnents/systems talk to the computer on '94-'95 trucks. With that answered I think you can plan appropriately. I don't know if the gassers from '91 to '93 (probably through '95 - don't quote me though!) talk to the computer or not either, but I know the tranys do (They're electronic!). I know without a doubt that the '96 and newer use OBDII, and (in the trany) you have the following sensors:
- Automatic transmission (AT) input (shaft) speed sensor (ISS) assembly
- Automatic transmission (AT) output (shaft) speed sensor (OSS) assembly
- Automatic transmission fluid temperature (TFT) sensor
BTW: I think the input and output sesnors are considered one assmbly, but not sure.
I think all the trany sensors talk to the computer, but those transition years (95, 96) raise that question: What kind of input are the computers expecting?.
Now, making some assumptions, I would think that all the 4l80e's have those sensors and would therefor need to interface with the computer to control the trany. That being said, i would assume any computer (year-independant)which can control the 4l80e should work for you (Also asuming that the answer to the question above was "All the computers expect the same input and send the same output").
If you can get your shop to build it with mechincal sensors (I have no idea if this is possible!?!?) in place of the electronic ones, then you might be in the clear for the trany swap.
And you do have the throttle cable issue to deal with since your not gonna be using a EFI gasser. Couldn't you just put together a throttle cable assembly in place of the electronic one?
Anyway, sorry for the long post. I find this type of swap to be very interesting and challenging, so I tend to ramble on.... hehehe...Led Zeplin...
The issue might be resolved if you go with a '93 computer and harness. But thats more money.