I have an 84 mustang gt convertable and I am looking at a listing for a tranny says its for an 87-93 but wont it work on my car to? I thought the tranny was interchangeable from 73-93 with out a problem...I know they switched from the nwc to the wc in like 85 or something but shouldnt I still be able to bolt up the wc tranny where my nwc tranny was with out any modification???