What if any is the difference between the 84-88, and the 89-92 throttle body's.

 

I think it is in the way the throttle cable or something mounts... Otherwise They are pretty much the same... Somebody correct me if I am wrong :lala:

 

Throttle cable linkage (84-88 is straight pull, 89+ is radiused pull) is the biggest thing. Get the TB that matches your cable or get the cable that matches your TB.

The IAC passage is also different. In order to use an early TB on a late plenum, you have to drill a hole between the throttle ports on the plenum. Look at the back of the TB and you'll see what I mean. Late TB will work with either plenum just fine.

 

They seem to go on ebay fairly cheap