[HuBarlow]

It does sound like you got the Disk/drum master, and it may work with the four wheel drum setup, but as mentioned before, have you checked the wheel cylinders? Another thing to look at (and probably replace) are the rubber lines front and back. Most people forget them, and in my experience, if they are over 8 or 9 years old, they should probably be replaced. I have had them LOOK good on the outside, bet disintegrate on the inside and act like a check valve that will allow the fluid to flow in one direction.