I am looking at buying a used 2021 Chevy 2500 HD. Per the Carfax report all but one of the vehicle services was performed at a GM dealership. I asked the selling dealer (where 1/2 the services were performed) for the complete service records, and they are telling me they can't pull up info from other dealerships. They also haven't provided a report for everything they performed at their dealership. My understanding is that all GM dealers can see the full vehicle service history of work performed at a GM dealer and entered into their system…am I incorrect?

Are my expectations too high or are they being difficult?

Sounds shady. You could call the other dealer for them, but why can't they bring up their own records?

I believe they can pull anything done by a GM dealer up in their system. But I am no expert. Asking the selling dealer to do that and print them is probably going to get mixed results. What is their incentive to do it for you? Giving you that info at best will cause you to still buy the car from them at a price negotiated from a place of mutual knowledge of the car's history. One possible OK outcome for them, but more likely, You will find something in the history that makes you walk altogether, or try to low ball the negotiations based on negative information they gave you. There is no upside for them.

The reason I believe they can do it is I asked my local GM dealer to look up the history on a used Gen 2 CTS-V that was being sold at a 3rd party used car dealership. All I wanted to know is if the supercharger has been replaced under warranty as per a service letter / bulletin I knew was out there on that gen car. They looked it up for me and confirmed the date and dealer that did it and even printed off something showing that data. But this was one specific thing I was asking for, and I wasn't asking for a printout of multiple records.