'70 IIA with o/d: Driving along in 2nd and 3rd mainly, ugly clunky noise, suddenly tough to shift...one block later can't shift in or out of forward gears, for the most part. When I was in gear, it would go sluggishly and jerky. Stopped in middle of road, people loving me.

Engine off. Very difficult to pry out of gear, can for awhile shift to reverse, but then not even that. In neutral, clutch or no clutch, either way cannot get into gear. Put o/d in neutral, put transfer case in neutral, only then could I push it to the side of the road, where it sits now.

Clutch is full of fluid, so no failure of lines, etc. Truck is far away from my house in residential neighborhood so not ideal to work on.

Any ideas on what I'm looking at, next steps, and how to go about it? My instinct is to tow to my house and tear it apart, and likely will find some serious ugliness in the gearbox, but I'd love to hear reasonable speculation and ideas before I do that.

Thanks in advance, any feedback and input appreciated.