recently replaced the front passenger brake line after it collasped on me.and i found out i have no clue how to blleed the rear brakes.i can bleed the front brake calipers but i dont know about the rear brakes.do they have a bleeder screw to?

On the backside of the brake drum, just above the brake line should be a bleeder screw.

Considering the age of the vehicle, those bleeder screws are probably seized in pretty good. I'd be careful trying to crack those bleeders.

squirt them with wd40, a few light strikes around where the bleeder is and sometimes it will come loose. make sure you are using a good six point socket or wrench. if i am working on an old vehicle that hasent been messed with i nomally go and get new ones first and replace them because most times they come out but the hex part strips and you have to use vise grips

I'm not sure, but wouldn't this system have either a combination valve or proportioning valve to the rears, that may have to be depressed?

Gus, interesting point, I know the really old disc/drum systems like on my 71 SS had prop valves you had to deal with when bleeding brakes, the prop valves kept the rears from locking up under heavy braking but maybe abs has made those unnecessary? At any rate if the op has a prop valve it should be located on the frame rail beneath the master cylinder on his 1 ton.

2004 Bonne SLE
1971 Chevelle SS

see what im having problems is i changed the front passenger brake line and only bled the front two calipers .and know when ever i stop the back brakes act like they don't work.like if you stop with the front tires in a mud pit and back tire on dry ground it wont stop it just slides and back tires will just roll.. I've followed the lines and they go from the master cylinder to a valve right below the radiator and it branches out.i cant jack it up right know to trace them the rest of the way because grounds to wet.and thank you all for the help so far.

have you taken the drum off, clean and lube the adjusters, and set it so the pads drag on the drum?

i bled them and they are working perfect agian.ty all