Heaby duty and standard duty transmission
 

What is the difference for a 1989-91 rx7. I've found that I'm being asked if I am looking for a standard duty or heady duty 5 speed n/a trani. Found few on eBay but I wouldn't know how to tell the difference by looking at the case. Is there an identification number. And is one more powerfull than the other. Seems to me like they might last the same time if driven the same way

There's no difference. N/A cars got a M-type transmission. TII's got the beefier R-type. I forget the exact part numbers, but that's the only difference. As for automatics, there are three varieties. Type M's for the FC and all prior rotaries, R4A-EL for the FD and 13B-RE Cosmo and then the Q4A-EL for the 20B Cosmo.