Lack of a little free play in the pedal may have been your problem. If 'twere me, I'd want to know for sure about the residual valve. You should be able to find out without removing the cylinder. Disconnect the brake line out of the cylinder, and remove the banjo bolt and fitting if your cylinder has them. Find a piece of baling wire or similar probe and see how far into the outlet port it will go. If there is a residual valve, it will only go in about 1-1/2". If there is no valve, it will go in maybe 3-1/2" or so.
If there is a valve in the cylinder, you *might* be able to remove it without taking the cylinder out. I don't know how much room you have to work. Most of these cylinders have a hexagonal headnut--the big threaded outlet adapter at the back of the cylinder. If you have a hex headnut and a wrench or socket to fit it (probably 1-5/8") you can remove the headnut. The spring and residual valve will follow it. Pop the valve (a little derby-hat-shaped metal gadget) out of the spring, remove the rubber gasket from the inside end of the headnut and put the spring and headnut back in. If your cylinder has a headnut with a serrated rim, you will want to remove the cylinder from the truck and take it apart through the front (pushrod) end. It would be physically possible to do it in the truck, I suppose, but feeding the piston in against the flare of the rubber cup and getting the spring clip into the groove while holding the piston against the return spring is difficult enough in a vise at the bench. I wouldn't try it under the truck.
If you're lucky you will be able to pump the air out of the cylinder without having to bleed the sytem.
Joe
