brakes/booster

95 jimmy 4.3 4x4 4walb .having problem with brakes and need advice as to where to start first. past couple days brake pedal would seem normal but if pressed hard i would get a hard pedal, now have hard pedal. vaccum at booster good .with car off i pushed down hard and popped rear left line.start car and still hard petal. am i looking at replacing booster or does it seem like master. thanks k

If the same with engine off and engine running the booster is bad.
But if you popped rear line you will need to replace it and bleed brakes.

thank you for the info ,it was the booster. i replaced the rear line but bleeder screws are not moving (stripped them) .gona try the lines themselves,i can loosen rear left but not the right side. do i have to replace the cylinders if its a no go? thanks k

thank you for the info ,it was the booster. i replaced the rear line but bleeder screws are not moving (stripped them) .gona try the lines themselves,i can loosen rear left but not the right side. do i have to replace the cylinders if its a no go? thanks k

Depending on where and what line you replaced.
If you can crack a line between repair and rear cylinder it may bleed.
Good luck

all set thanks again. k

Your are welcome.
Good Luck