Oh, I meant differences between the kegs, not the seals. The biggest issue is getting the right poppets for the odd frankenkeg parts. Most of the kegs are labeled on the rubber on the bottom or stamped on the side, although I'm still not entirely sure which is which. Many say Firestone but were manufactured in Spartanburg. I assume that makes them a type A poppet, but there's also another keg that was made in Spartanburg, which doesn't say Firestone on it, and it's about an inch taller than the rest.
Anyway, I'll probably just stop sweating the details, and find a way to make most of them work, then guess on the replacement parts for the rest.
"I am a firm believer in the people. If given the truth, they can be depended upon to meet any national crisis. The great point is to bring them the real facts, and beer."