afro thunder

I was just about to order a new exhaust system, but the engine in my car was replaced about 65,000 miles ago, but I don't know what year they used. I know, it sounds stupid, but I was wondering where the serial number on hte engine is, and is there anyway I can tell what year it is. Thank you.

Scott 89t2

the exhuasts are the same for 86-91 anyways ??