brake problem

[justinth]

i have a 72 f250 4x4 and when i hit the brakes there is a sucking noise it sounds like a vacuum leak but ive never heard of this kink of problem with brakes or anything does anyone have any ideas on what this noise may be and how to fix it ? the front brakes are disk and the rear are drum

[FORDification]

I'm assuming you have power brakes, which means you have a vacuum-operated brake booster. And it sounds like the booster diaphragm is leaking.

[fordman]