I have an 88' IROC-Z and I really like the ground effects and front spoiler on the 91-92 model years. Will they bolt right up to my car or would it be better if i forgot all about it?

 

I think you also need a 91-92 front bumber.

 

The front spoiler won't mount up to my front bumper?

 

Nope, it's the same. The rear is different though, to match the quarter pieces.

There is some drilling required, but it will all mount up.

 

I could swear that there was a different part number for 91-92. Wow i was going to throw out a 89 front bumber cuz I thought it wouldn't work.

 

Depending on what company is selling it, it could have a different part number even though it's the same part. GTS has done that too, with their headlight covers.
At any rate, I currently have two '86 IROCs with '91-'92 front spoilers installed.