Instrument cluster there is a red connector, and a gay one. i have the gray one on the right side, looking at it from the driver seat,. and it works ok, till i turn on the headlights. then right gauges go crazy.

 

First thing to check is of course the grounds; specifically the ones to the cross piece inside the dash. Also to where that cross piece bolts to the metal subframe of the dash, and where the dash bolts to the cab.

The ZEROTH thing, IMO, is to pick up a Chrysler Factory Service Manual (either used off Ebay, or a new one from Bishko - autobooksbishko.com ) so you can have good wiring diagrams to work with.

RwP

 

A few months ago, I had a similar problem and had a horrible time until I came across www.instrumentclusterstore.com. When I called they had the cluster I needed in stock, they were very helpful and they even transferred my mileage onto the new one. Cost was very reasonable and shipping was free and fast. I believe they have an ebay store as well. Good luck, hope this helps!