can i use a harness from 1991 firebird convertible 5speed full interior harness and everything should work no problems in a 1991 Camaro Convertible RS 305/700r4 that is getting T5 swapped ???

main concern is if the dash wiring and connections will be different as the speedos are different

 

That's not going to work well. The Firebird dash, and therefore the wiring, is different from a Camaro. Shouldn't really matter anyway, because your TBI dash harness should already be wired for the 5spd in addition to the auto. The engine harness will probably need a couple wires added for the reverse lights, but there are plenty of threads on manual conversions that cover the wiring changes.

To use a Firebird dash harness you'd have to rewire the entire exterior lighting circuits since the headlight and dimmer switches are different. All the switches in the dash are different too, and in different places. Cig lighter is in a different spot. The list goes on.

 

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