Mitsubishi truck Stuck in gear - manual transmission, shifter moves

Anyone has suggestions for what to check when a manual transmission won’t shift out of gear?

It’s a 1984 Mitsubishi turbo diesel truck with 5 speed manual transmission.
When the clutch is released and car is running, it moves forward as if in second gear. I can move the shift lever, but no matter where I move it (neutral, reverse, etc) and release the clutch, it is still stuck in 2nd gear and moves forward. The shift pattern also feels off (can’t get the stick shift into gears 1-4, only seems like 5th, reverse, and half of neutral, but still when the clutch is released it moves forward as if stuck in 2nd). Was working fine, parked it, and then had this issue on the next startup.
Perhaps a shift linkage or shift fork issue? Looked under the shifter boot but didn’t find anything out of the ordinary.

This happened once before where the shift pattern felt off and it was stuck in gear no matter where the shifter was, but then everything re aligned back into place after about 5 seconds of fiddling with the shifter. Ran fine for several months but it did it again now and I wasn’t able to get it driveable again. The truck wouldn’t roll forward or backwards more than a foot (even with the clutch pressed in). That makes me think the gear was stuck in two gears at once (ex reverse and 2nd) Tow truck pulled the truck in reverse up onto the tow bed which seemed to knock it out of reverse. Now it rolls backwards fine, but when the engine is running and clutch is released, truck still moves forward (2nd gear?) no matter where the shifter is.

I can move the shifter into what seems like is 5th, neutral, and reverse (shift pattern feels ‘offset’, can’t get into 3rd 4th etc.) but it doesn’t affect the current gear (stuck in 2nd).

Any ideas? Thank you ?!