A week ago I parked the truck, 1987, in a shopping center parking lot and got a ride to a meeting with a friend. Never had a problem with the clutch before. That evening the pedal went straight to the floor with no clutch. Fluid level was OK. 1. Replaced both master cylinder and slave. 2. Truck front end is jacked up. 3. Bleeder is on the slave. 4. So far I've run a quart and a half through the system trying to bleed the air. 5. The outside of everything is dry which should mean no leaks. 6. I've used a vacuum pump on the slave cylinder which seems to be drawing air in around the bleeder threads. By bleeding in the conventional way I can get to the point no air is coming out. 7. Still no clutch pedal. Any ideas?