We changed the slave cylinder & Clutch Master Cylinder, have been issues bleeding the system. Finally got some pedal, but can only get it into 1st gear by killing truck, putting it in gear, then starting truck. Can't get it into reverse. Any ideas.

 

You are trying to force air DOWN to the slave cylinder....... and air just isn't that cooperative. Take the slave off the trans, restrain the piston/operating rod, (whichever) so it simply can't move (blow out.....) hold the slave above the master, and bleed that way, then reinstall.