Hi Kojack, please consider creating a signature including details about your truck, so we can have an idea of just how complex your rig is.
Thankfully I haven't really needed a shop for repairs, but I do need one for emission testing. I use a local truck repair shop who is also a Cummins warranty facility. I know they also have Chrysler diagnostic equipment and have a good reputation via word of mouth. They ain't cheap, but if I ever needed something I couldn't do- that's where I'm going. Years ago, when my rig still was covered under the 3/36, there was a production run that had leaky fuel pumps and mine was included. With a bit of homework, I found out about a dealer 25 miles away in another state that employed a Cummins specialized technician. I was fortunate that they were willing to take my claim and that he would do the job, and they did a fantastic job. Not all dealers are bad.