I've got an '83 SE with an LS1. Got most of the bugs worked out. Nice car.
Here's a link, for anyone who wants a look.
https://www.thirdgen.org/forums/ltx-...u-gets-c5.html
I've got Autometer Tach and Speedo. Both work fine. Put them into my '83 dash, and those remaining gauges work ok, too.
What does NOT work is the dash lighting. No dimming feature, and if you go with the one setting that will work, everything goes out after 5 minutes. (circuit overheating?)
Changed over to '85 front plastic for my dash. Like the look better, much better. Thumb wheel dimmer is part of Headlight switch on the '83. On the '85 the Dimmer Wheel is moved to below the Headlight switch.
IS THE PROBLEM-
1) The Thumb Wheel switches are different, and the '85 won't work with the simple '83 dash lights (just a few small bulbs)?
2) The '85 Thumb Wheel switch is no good?
3) The Autometer gauges don't want to play nicely with the '83 gauges?
4) Something else??
Thanks for any info or ideas…..

 

If memory serves the Birds have a "dimmer module"... you probably need a new one.