Howdy all. I have a '97 F250 PSD 4X4 crew cab/short bed with spongy brakes. I bought the truck 2 months ago and the brakes have never felt right. The fronts are working, but lock up with medium pressure on the pedal. The rears don't seem to be working at all. I removed the fluid reservoir and cleaned it. I bled the brakes and heard a strange high pitched whistling noise from the booster/master cylinder. I road tested the truck and it saw that the brake light on the dash stays on and heard a slight whistling sound from the booster. My next step will be to replace the master cylinder.

I read through many posts on here and found that there is some confusion when ordering the master cylinder. Does the wheel base make a difference? I need the truck to drive to the parts store, so how do I know if the bore on my master cylinder is the 1 1/8" or 1 1/4"? I get my parts from NAPA and they have always fit/performed properly with the info that I give them. Does anybody know the correct part number for my truck? Thanks...