So the back brake cylinder on my 66 went out, there stuff all over the floor. Anyway, autozone carries a replacement part for like 9 bucks, but i see others online and the lowest is 30 bucks. whats the dif? Is online that much better.

 

I'd say no...some places charge more on line than in the store

 

There isn't much difference. Just make sure the wheel cylinder is a brand name and has some sort of warranty.