Post 1 stated " I also hate to call a dealership for part numbers when I'm trying to NOT buy from them. "

Calling any vendor just to get part numbers so a purchase can be made elsewhere is bad form. Why should a busy vendor help out when there is zero chance they will get a sale? This is different that shopping around for best value and buying some parts from the dealer however.

Showing up in person gives face time with the parts guys and they will likely be more willing to help. It also helps if one has a clear vision of what you want and are willing to look through a parts printout to ID parts. Buy oil filters and such from the dealer even if it is a dollar or two more than a generic parts store, this way one can tie in " hey , can you please check this for me? "