Tigger,
I know how you feel about the Digital dashes on the early 80's Riviera's! I have 2 of them for my 85 T Type, and neither one has all of the displays working.
If I were to install an analog dash into a car with a digital cluster, I would find a parts car and take the entire instrument cluster wiring harness along with the instrument cluster itself. I would also grab the ECM, just in case.
The PROM's in the ECM's are different for Digital dashes and also for Electronic Climate Control. (don't ask how I know this!)
You would also need the fuel sending unit from the tank, as the resistances of the digital and analog senders are different. (don't ask me how I know this either!)
Having your digital dash repaired by Casper's may be the best route to go!
Good Luck,
Tim
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Tim McCluskey
Maplewood, Minnesota
ROA 9686 BCA 39089
1963 Riviera (Blue)
1963 Riviera (Black)
1985 Riviera T Type (White)