[MagicRat]

You would need a machine shop and a couple of engineers from NASA. Do you already have the C-4 transmission? It is a bad idea to base a component swap just based on parts you have lying around.

The biggest problem is that the bell housing and torque converter is quite differnt than a GM transmission in terms of bolt pattern and size. It simply would not bolt up to your engine unless you did extensive metal work and fabrication. There are no adapters because GM cars had their own excellent automatics. Also, the transmission mounts and shifter are not compatible between the C-4 (Ford ) trans and the GM chassis.

The C4 trans is not such a good unit. It has a 3 speed trans with no overdrive (4th) gear. Most had no lock - up torque converter and it is not particularly strong, unless modified.

If you want an automatic you are MUCH better off using a stock GM 700 R4 (if you have a 305 V8) or a 200 R4 (V6). The best way is to get one from an automatic Firebird of that year, so you get the console, shifter, trans mount etc.

However, your car is worth more and is more desirable if you keep and fix the stock T5 transmission. It's also cheaper than doing the trans swap.