I have an 86 firebird 2.8l with the rally gauges with a speedo that only goes up to 85mph. I wanted to get a speedo that goes up to 120mph and I went to the local pull-it-yourself junkyard and found a 89 firebird 2.8l with the rally gauges that go up to 120, and pulled it. I just go the part with the gauges with the board on the back. The thing is I am unsure If my firebird has the electronic gauges or the mechanical gauges, is there but I have seen the cluster that is on my firebird now and it looks just like the one i got. I have also heard some mention that if you get a different speedo you have to change the speedo gears or something. I would also like to change the odomitor so it reads the millage that my engine currently has, no clue if it is possible or not, if not i don't really care that much but it would be nice to have. If i need more parts this 89 firebird is still there so I can get whatever else I need.

/edit i ment 85 in the thread topic....dammit

 

I have an 85 with the idiot light set up
YES STILL I DO, no haven't changed it yet. I have a 1985 rally gauge set up ready to install once I add the one tach white wire under hood to dash.
I thought about changing the speedo, too.
But gave up
Why
Mine is accurate
It works
IF I wanted to change mine that's easy choice for me!
I'd go get an early car SPEEDO HEAD and insert, then change to the 120 face cover!
Early car is ANY car from 60's/70's. Bring your old unit, match it up with another choice car speedo head unit, remove from wrecked car. Majority of "parts like that on cars" made by same manufacturer.
I had in hand a 1969 Firebird speedo & was almost ready to use that 160 MPH speedo head. BUT I sold 69 Firedbird dash set up for MUCHO DOLLARS & again my current one works just fine. IF I want to see a higher speedo reading I go to other cars. (Like my old Corvette!)
The dash set up you have MAY NOT totally work right due to the electric speedo assembly. 1985 is mechanical speedo. I know mine will work due to it's a 1985 rally set up, designed to be an option in my year car. It'll match up perfectly. The speedo is the key. Rest of stuff is kinda moot point as it'll work. Except if ya got a 60PSI (V8) oil guage instead of an 80PSI (V6) oil gauge. Also tach readings will not be accurate. There is a "Chip" on back of the tach that reads V8 or V6 or just numbers 6 or 8. Two clues to know if ya scored a 6 or a 8 cylinder dash.

IF others say different, then I also will be educated.
ALSO if ya scored the dash, MAKE SURE YOU grab the back rally dash plug blocks with wires.
WHY?
That's your "road map" to swap around the wires in your current car. Ya match those other block plugs to your in car one and add one white tach wire (powered off coil wires under hood) and ya "done".

I had a thread inpast about this. See if you can find it.
I had in title I think "Leaving the idiot behind".