hello.
my pass side rear brake is locking up when applying light pressure. only the rear pass side. I replaced the cylinder with a rebuilt last weekend. actually i went through two rebuilts because the first one leaked. the truck drove fine for a 100 mile trip and then for a few days of light driving. now it will lock up and screech on slight brake pressure. its not leaking i already checked... the funny part though is in the past few days the locking up has come and gone. i noticed the problem yesterday morning. when i left work yesterday problem was still present but after a few hours i ran an errand and it was gone. this mornign it was fine for awhile then began occuring again. any ideas here guys? i just added disc up front a few months ago and most of the lines were replaced. i have a small section of rubber line but it is inbetween the steel line that runs from the M/C and the T at the rear end so i think if that was the problem it would affect both rear wheels.
the rear drums are self adjusting from a 79 caprice. the m/c is new. i also checked to make sure the parking brake is disengaging and it is.

help