Gotta love when the repairs are less than thought. ALWAYS be leary of a snap diagnosis, as a former tech, it is rarely what you think it is at first glance. Quite a bit can be learned by a good cleaning and a 2nd look. And in your case a pressure test of the cooling system. There are a multitude of shops out there that will see us (expediters) pull in and see $$$$$ and know it is likely they will not see us again when the problem returns. A tip to try to keep shops honest, tell them you want to see the parts they are replacing or have replaced and ask to see where the part goes on the truck.
I have seen people say to steer clear of dealerships on here and want to say this about that. While I agree that they tend to be more $$ it can actually save you money in the long run by using them. You have more recourse dealing with them and are able to get refunded on labor cost associated with BS "repairs" or misdiagnosed repairs that havent fixed the problem. The paper trail can be your best friend.