801curt,
Can you post a photo of the emblem on the hood? The 4100 series might have a non-GM body.
Can you post a photo of your truck?
Denny's instructions should be excellent for making a crank. The Chevs of the 40s crank (the link I posted above) should also work fine.
You might be able to turn the engine, to adjust the valves, by simply putting the engine into neutral and turning the fan belt (and/or) the harmonic balancer by hand.
