84/85 tranny is tagged "BQ" and 86/87 is "BRF". Your tranny should have a metal tag at the tail housing with the designation. Hopefully the valve body inside will match .
86/87 BRF tranny has a different valve body (as Chad mentioned) which IS considered [better] an upgrade from the BQ. Also has a different servo which is supposed to give a firmer [I think] 1-2 shift.
The BQ tranny is no chump though. It is definately not the same as just any old 200r4. I know some guys who converted to 87 setup (engine) and did not touch the tranny and are doing great. Besides, you can always throw in a shift kit, or a upgraded servo if you wanted (heck, they do this to the BRFs too).
Tranny section, Im sure, will disect the two for you and tell you probably more than you ever wanted to know .