[Ironangel]

What motor are you running? Have you taken a vacuum gauge inside the cab with you and monitored the vacuum through the various engine speeds and loads? A lot of overlap in a cam will kill vacuum availability. Also, the rear wheel cylinders can leak past the piston and trap fluid between the push pin seals and pistons. If your not loosing fluid I'd suspect the master cylinder piston seals are not sealing completely. When bleeding the wheel cylinders take some thick dielectric silicon grease and seal the threads on the bleeders so air cant be drawn back in on the release. Only open the bleeders a quarter of a turn to minimize the air being sucked in by a vacuum bleeder...