I have a 2003 Sierra 1500 SLE. Sent the cluster to a guy for the speedometer and tachometer malfunctioning. When I got it back and plugged it in my fuel, oil, temp and voltage gauges were not working at all, my gear selector was not lit up and all "idiot" lights were on which all worked when I sent it out. I sent it to another guy who supposedly fixed the first guys mess up and when I plugged it in the only thing that changed was my gear selector lit up but it isn't telling me what gear it is in (which isn't a a big deal for me but my daughter drives this and she is a new driver). Am I missing something when I plug the cluster back in? Is there a way to reset this? Also when I took it for a test drive it is not registering the miles that I am driving either.

as long as the connector is reseated properly it sounds like they messed it up

I had a problem with my 04 Sierra where the entire cluster would randomly turn off and the gauges would all act like the vehicle was off. I ended up taking it out and cleaning the contacts and never had that issue again.

It sounds like at this point you may have more than that going on, but it'* worth a try to clean the contacts on both the cluster and the vehicle.