Can anyone comment on new vs. rebuilt brake master cylinders. I have a 77 whose BMC is shot. I do have a Nissan rebuild kit, but several posts in the archives have indicated rebuilding aluminum BMCs is a bad idea. Why is this? Also that rebuilt BMCs from auto parts stores like Autozone is also iffy. Autozone has rebuilt BMCs for $45.00 and offers a lifetime warranty, so they must think they will last. Has anyone had failures either on BMCs they've rebuilt with factory kits or on parts store rebuilt units?