Man what a day!Little by little ,I rebuilt the master cylinder a while back still no brakes! Never had an airpack apart much less knowing what one is ,but armed with a blow up diagram from one off of an M809 ( was hoping it was the same) took it all apart cleaned and unstuck (technical term) it. Today weather in the 60's ,drag boys outside let them pump while I bleed the wheel cylinders. I can't believe it, now the pedal goes down about 1 1/2 in. and is rock hard! I'm just starting out working on these trucks and it seems to get easier everyday! I can't believe how well built and designed these trucks are,to be over 40 years old and everything still unbolts without breaking(no bleeders broke or stuck) Man I can't wait to get it done and legal!