My guess is that your throwout bearing is hanging on the splines for some reason. This has happen to me twice in deep dust in Nevada, although with modern **** pickups, washed it out with a garden hose for temporary relief. Another thought is a linkage failure. Check for broken pivot brackets or other linkage snafus. You may not be fully disengaging even though you see stuff moving.
Thirdly, are you sure you didn't just want to see what you could do with that 7.02:1 granny?
