I replaced my first under hood air compressor today. The one I removed was a large duel piston compressor that said "air brakes" on the side of it. This one locked up, fryed the belt etc. The one I replaced it with was a single piston, larger cylinder unit. What's the deal with the differences? t seems to work great. I have to remove the new one I installed, I tried to silicone the mating surfaces and of course it leaks oil. I am going to make a gasket this time!!