Originally Posted by LATECH
Camaro and Firebird are both F Bodys.
The difference in wiring will be defined by the equiptment used on the build. Different engines use different harnesses as do different style and formats of instrument panels.
A camaro and a firebird could both have a 305 chevy under the hood, and use the same harness, but the instruments would require a different harness depending on gauge layout and type, warning lights gauges etc.
A firebird can have a 301 pontiac or a 400 pontiac and the wire harness used under the hood will be different than a camaro as a camaro never had a pontiac engine.
Automatic and standard wiring harnesses have some differences also, and that can also change between different automatics.
The GM underhood harness typically comes in two parts that separate at the firewall connector, a forward lamp harness and an engine harness. The forward lamp harness will likely be different between the Camaro and Firebird, but may be common enough to work. The engine harness will be unique to the engine type (six or eight, Chevy, Pontiac, or Olds engine). Most GM harnesses are the same for AT and MT, the unused AT wiring is usually just taped up to the harness in the MT configuration. Similar year harnesses may also work (1977-1981) but I have found that there can be year-to-year differences. I don't have first-hand F-body experience, but as an example, when I tried to use a 1970 Cutlass forward lamp harness on a 1969, I found out that while all the wires were the same, their locations in the firewall connector were different in some cases. As a result, I had to remove and replace about a dozen terminals in the connector.