would a 90 RS with a 305 TBI have a WC tranny?

 

Yes.

 

As long as it is the original for that car yes.

 

What is the differance between a WC T-5 and a regular T-5?

 

WC is stronger, IIRC uses some brass components or something like that. I'm sure using the search feature will get you plenty of info on the differences.

 

how can you tell what your car has?

 

WC started in 88

 

i have a 1988 firebird 5 speed. Does that make it a wc t-5? I know its a berg warner.

 

Yes, it's a WC if it hasn't been replaced with a non-WC

 

There should be a metal/tin tag bolted to the transmission housing (held on with one of the tail-shaft to gear housing bolts on my 89 V6 WC T5). There should be some numbers on this tag starting with 1352, for example, mine is 1352-77. The tag will probably be dirty or rusted (mine was, but I didn't have too much trouble getting the number off). Write this number down and go to http://www.5speeds.com/t5/ - find the tag number in the drop-down list on the bottom of the page and click the Identify button. It'll tell ya what tranny you have, and if it is a World Class, it'll say "WC" in the ID line.