At 260k miles, worn out synchros are likely especially if someone used GL-5 gear oil which slowly eats the brass syncros. If it feels like the clutch isn't fully disengaging, you might also suspect the bearing that goes into the end of the crankshaft. The clutch was replaced on my comanche right before I bought it and they didn't replace that (the previous owner sold it because the clutch replacement didn't fix the problem, and they claimed it just needed a new clutch). I didn't think to replace it when I rebuilt the trans and it eventually seized and destroyed the trans input shaft bearing.