Spring one is by an large the best for looking for those sort of parts...I haven't gone to spring carlisle for a few years, but i know it wasn't what used to be now the internet is around. Vendors have a hard time justifying the travel costs, when they can just post stuff up on the net....
GM carlisle is also pretty good...I prefer that one over spring. GM carlisle isn't as big, but its all GM stuff. Spring is much larger, but a lot more "junk". and it isnt' broken out by GM/Ford/Moper etc...so you have wade through all of it....
Nate