Okay my 89 firebird XS v6 700r4 trans was totalled by some dim wit not paying attention.

I sold my transmission and engine to a guy with a 85 camaro. His trans has a Speed cable. Mine has VSS. What needs to be changed to complete this swap.

 

I did exactly this to the 700R4 I just put behind my new 350.
My trans was VSS and wanted cable drive, so I just took the gears from a cable driven speedo unit and swapped them with my VSS style gears. You can use the same tailshaft housing. Changing the gear on the output shaft can be a real PITA if you don't know the trick to it. Sliding the gear on is much easier if you first place the gear in a coffee cup of water and microwave it for about 15 seconds to get it warm. I know it sounds crazy, but it really works. Getting the drive gear off of the tailshaft is another story... that took me a good 15-20 minutes of just working the gear back and forth slowly moving it back off the shaft. Find the right gear combo and get the cable drive style gear housing from another tranny to replace the VSS unit. The V6 and V8 gears, gear housings, and tailshaft housings are interchangeable.