I done a C to K swap with my 75 Cheyenne Super 2 years ago, I ran the stock C stuff up until the M/C went out, it stopped ok, but I would have liked better brakes. When it went out, I swapped the whole set up for a 3/4 ton set up, I had to end up changing the pedal inside cause of booster plunger hole size difference, that ans I did'nt have a big enough drill bit to woller the hole out /forums/images/graemlins/rotfl.gif but if ya ain't got the heavier stuff, "c" stuff in my experience would work, just be sure the rear brake are set up correctly to provide maximum braking, I ran the "c" stuff and 33's with out a problem, hope it helps, just my experience, not guranteed /forums/images/graemlins/rotfl.gif