Does anyone know where the triangular metal plate with 3 small screws/bolts goes?this part is making me go crazy.I think it goes somewhere by the heater core .a pic would help greatly.the box was taken apart about 5yrs ago when restoration began.

 

This should help you out
If not post a pic of your part.
PS this info is for 82-89 Firebirds

 

first time ive ever seen this diagram. Hope my heater core never goes out!

 

It's not as hard as it looks.

 

Dancar01,post a pic of the part your referring to.

 

Part 18 looks similar to the part in question.but not .my car is a 83 trans am with ac.part measures approximately 5x6x4" with a 1/4"lip with 3 screws.a pic was posted.