I've had hydraboost, 1/2 ton master cylinder, stock p-valve on 1 ton gear with a caddy disk conversion running with perfect distribution on my truck from day one - but others have been experiencing all kinds of rear lockup problems. Today I was replacing my master cylinder and decided to update the stock 1/2 ton non-hydraboost unit to a 1 ton hydraboost master cylinder. I cut the brake line fittings off and replace them with new ones while I was at it since the previous ownder had chewed them up, probably when splicing in the trailer brake line. While gravity bleeding the brakes, I noticed the smaller front chamber of the MC was draining for the front brakes - this struck me as odd since I always thought the larger rear chamber should be attached to the front (70/30 braking and all). The front brake tubing is much smaller than the rear brake tubing into the MC so switching it seemed a little rediculous - time to open the book. The book shows the larger tubing on the smaller chamber and thats when it hits me. The guy who previously owned the truck had switched the two around when slicing in the trailer brake sensor and I've been running the front brakes off the smaller reservoir. Having taken apart a MC before to rebuild it, I don't recall the smaller chamber having any less plunger feeding it than the larger chamber - so theoreticly fluid capacity should not be the difference, but perhaps one engages before the other which is how my brakes have always locked equally with no other changes. Any thoughts?