will a 96-98 starlet seat belt fit an older corolla

Probably. Everything else between the two models is the same or similar. The only way they would not work is if the anchor bolt(s) are different size which is doubtful. If you are talking complete set. Or if one from a Starlet will buckle in to the Corolla lower belt buckle and you are swapping retractors from the top belt...lap belt and shoulder belt only and not the bottom strap? I think they will still work. If the buckles don't mate, just swap the entire set from the Starlet

Okay, after looking up "seat belts" for 1994 Corolla there is a very long list of applications for the 3-point belts including the Starlet '84 to '99 including wiring harness..yes it has a wiring harness for the beeper to remind you not~so~subtly to put it on, and you must have that or disable the warning beeper