She's started grinding...

[Luvlegs]

72 I6 3OTT - last fall replaced the throwout bearing - all good - I've put less than 200 miles on it this past year - slowly redoing everything from the ground up. Original transmission (I'd say about 120k on it).
I have NOT yet changed the tranny fluid - that's next. A new "heavy duty" clutch was put in just prior to me taking ownership. The truck has always shifted nicely although the linkage appears sloppy... I posted about the "cup" on the column that the shifter arm mounts to/in with almost no replies (seems loose and shift arm bounces/shakes).

Over the past 3 months, I've always felt I wasn't getting off the clutch smoothly going from 1st to 2nd as there was always a little "chatter/grab" for a split second. The faster I get off the clutch, the smoother the shift and no noise.
Lately, it has progressed to the point of not wanting to come out of gear at any speed or shift up or down at any speed.
At rest, no noise with clutch in or out or moving through the gears - I BELIEVE I have the clutch linkage adjusted properly from all I've read).
I almost have to slam the shift arm to get it to shift into 3rd and it will not go back into 2nd until almost not moving... it will but it takes effort and grinds.

I have read the FAQ on adjusting the linkage/column but not so sure that's where my problem is. I am not too familiar with synchro's and there function but hear the term thrown around alot.
The tranny will be getting swapped out with a T400 I have but I'm not ready to do it yet. I parked the truck as I'm working on it and it's not used daily (or even weekly as of late).
Any suggestions as to where to start and what to look for? (Short of opening the case up). Thanks all.