ok fellas, I, as with most of us, have known that the 1 inch master cylinder is an upgrade on our 22re trucks and My truck already had the upgrade done before I bought it in '01. However, I bought a V6 parts truck a few years back and the master cylinder was one of the things that I kept. Its been sitting in a drawer for a couple years(left). Now that I have the engine out of my truck and I'm waiting on parts, I figured it would be a good time to pull my rusty old master cylinder and clean it up (it works fine)(right). While I had it out I thought I would just check and make sure that it was the same as the one I had in the drawer. Both of them say '1' on the side. the one out of my truck says Aisin on it and the one I had in the drawer does not. Also, the one I've been holding appears to be aluminum.

Any Ideas what the difference is? which is better? Why?

 

Aftermarket.....

You need the dual diaphragm brake booster too.