You might want to go over to the cumminsforum.com site & scroll down to the ARIZONA forum. There is a thread asking the same question as you did, "recommended dealerships".
Seems like Power Dodge on I-17 & Bell Rd. is a good choice as is Performance Dodge on 43 Ave. & Glendale. Avondale Dodge had a good mention, also. I did not read the entire thread so, there may be other recommendations. Tempe Dodge had a negative comment.
I bought my '03 at Tempe Dodge & have had some warranty work done, there. They replaced the alternator bracket that was a stamped metal piece that was known for developing cracks, as mine did. The service writer that I had could not or did not want to see the crack. I had to highlite it with a magic marker before he would change it out with the cast iron bracket. I did not appreciate having to argue with him over a known problem.
The most recent visit to a dealer was with a fuel delivery problem. Took it to Power Dodge & they checked it out, completely. I had an aftermarket fuel pump on it that they wouldn't touch & that turned out to be the problem. There was a loose connection inside the pump & it would disconnect itself, occasionally. They spent a fair amount of time checking out the truck & could not find a problem since the pump had re-connected the electrical contact & was working, again. Can't fix what ain't broke!!!! They did not charge me a penny for all the work they did. I thought that was more than fair, of them. I ended up figuring it out myself & installed a spare pump.
My '03 had "injector knock" a few years back, & I took it to Performance Dodge. They acknowledged the knock but, according to Daimler/Chrysler's testing proceedure, there was not a problem so, the dealer could do nothing to help me. They won't throw injectors at just any problem. Through a lot of reading, I figured out what the problem was & fixed it myself. The knock was between idle & 1400 rpm. Turned out to be carbon build-up on the injector tips from not working the engine hard enough. I started running an injector cleaner but, what really fixed the problem was to hitch-up the trailer & run the engine hard enough to burn off the carbon. Every time it started to happen, again, I'd just run the crap out of it for a few minutes & no more problem for about 6 months. I've got a Smarty JR on the truck, now, & have not had the problem since its installation. I do not run the crap out of it but, every once in awhile, I'll have a bit of fun with it. Just enough to keep the injector tips clean.
I can't really blame Performance for not helping me. According to the testing they have to do, nothing was wrong & no one knew about carbon build-up at that time. They were learning about these new engines, also. In fact, when I found out about "THE FIX", I told them so that they would know what to do to try to fix the knock.
Joe F.