i'm trying to install a '87 iroc guage cluster used with a l98 tpi into a '91 rs with a mpfi v-6 factory. i am also swapping engine harness, computer, motor, and transmission. i know i will have to run the speedo cable also since the '91 originally uses the electric sensor mounted in the transmission. i have my wrecked iroc to get the parts off of but teh under dash wiring looks like a nightmare to me. if i plug in the '87 engine harness into the dash harness at the underdash connector and get my instrument cluster to fit, will i be able to usse the dash wiring for the rs or will i have to repin or run extra wires? if so, which ones? i've tried searching and looking through roughly 5000 posts and can't find answers. i would really like to do this without removing the entire vehicle harness. i couldn't see where the dash wireharness seperated from anything else except the bulkhead connector to the engine bay and the engine/ecm harness under the dash. any help would be appreciated. maybe somebody has the diagrams as well the might make some kind of sense instead of the garbage in the haynes/chiltons manuals? my motor isn't stock by anymeans and can't afford to get a chip burned for any kind of conversion. labor is free since i will be doing it myself. thanks for any help in advance.

 

Swap everything time! Big job but much easier than trying to disect and re-pin. Replied to your PM.