I pulled my cluster on my 85 300D and I jumped the 2 rheostat connections to make panel lights brighter.
I also noticed that someone was there before and partially cracked e the round keyed electrical connector that runs the show. Also pin 15, the ground pin is missing a lot of brown plastic material around it.
I also noted that when putting in a 1 filament vice double filament (required) bulb into the turn signal/running lamp makes the dash turn indicators screwy...

Anyway my Fuel and Temp guage max out now and my seat belt light comes on periodically. I hate electrical troubleshooting, sometimes it defies analysis................