Okay, seems like one thing after another right now. I have my Dad's 95'
6.5TD needing a new TC, doing a tranny swap on my brothers Jimmy, (700-R4), and now my own truck tranny is acting up. Here are the symptoms.

Goes into gear okay when engine not running.
When running, have to basically jam it into Lo or first gear. When driving won't downshift unless you really shove it. Won't drop into second at all.
I used to always start off in 1st. Now, unless I start in lo, it will crowhop a bit as soon as the clutch engages. Going through a drive-thru, it wouldn't come out of gear at first. When the clutch is in and it is acting sticky, I hear what sounds like a whirring noise. Reminds me of the noise a forklifts hydraulics make when the load is to heavy to lift.

The clutch reservoir has plenty of fluid, but the level barely changes at all when the clutch is pushed in.
The clutch, (and flywheel), are still rather new. Just over 20,000 miles on them. The truck has never been used for loads over 8,0000 lbs. Any ideas as to what this could be?
Aggravating to say the least as I also have roofing jobs to get to!
Thanks
Ben