Hey, well ok here is my problem....I own a 91 sunbird that has a 2.0L and auto trans in it, well not anymore but had one. I have dropped a 3.1L and a 5speed trans into it and now the problem begins....Will the wiring harness out of a 92 Z24 work with everything properly that is in the dash of a 91 Sunbird with no modifications???

the wiring harness should work, if not you may need to swap in a sunbird 3.1l harness.

I'm going to say probably not. Here's why. I'm swapping a 94 engine into a 91 Sunbird right now. In my case the engines are both 2.0 OHC engines, but there are still plenty of differences in the wiring. The 92 - 94 models have ABS while the 91 does not. Much of the ABS wiring is unneeded and should be removed from the 92+ harness. There are power and ground wires for the ABS which need to be cut off inside the harness. There are wires for the front wheel speed sensors as well as wires for the red and yellow brake warning lights which need to be removed. The rear wheelspeed sensor wires run through the driver's side of the firewall in the large bulkhead connector which is there. The windshield wiper motor wiring is routed through the driver's side of the firewall in 91, but it's routed through the passenger's side in 92+. The is because the locations used for wipers in 91 were used for wheel speed sensor wires in 92+. The tachometer connection is in the wrong side, too. And some of the wiring to the pcm is different between years, as well as A/C controls (pressure sensor in 92+ and simple safety switches in 91). Finally, the "pass through" connector on the passenger's side of the firewall is different in 92+ and doesn't fit without modifying the body of the car. Inside the car, under the dash, on the RH side is a connector for heater controls. It's actually 2 connectors in 91, and in 92 it switched to one large connector. The 91 underdash harness does not connect to it so you'll have to make modifications there, too. I've taken over a week to do mine, and I do a lot of wiring.

I have a 93 V6 car which I'm using for parts. Many of the changes I've described in the 4 cyl harness also exist in the 6 cyl harness. My advice is to find a 91 V6 harness to start with.

-->Slow

thank you very much on all of that information, Now what i need is either a harness from a 91 sunbird with the 3.1L and 5speed trans or the complete section of the of a wiring diagnostic for a 92 cavalier out of a dealer manual, haha that will be fun to find.