What's broke?
Could be the input shaft bearings or you broke a spring on the clutch disc and its fallen into the clutch plate Now what trans fluid are you using and what type of clutch assemble
Clutch is a McLeod B&B/Long combo, an 11"/10.5" plate/disc combo. Call it a 10.95" plate if that suits.
Fluid is Dexron. Before you guffaw, hoot, and deride, keep in mind that Ma Mopar says Dexron is fine for cold weather use. I wouldn't race with it, but that's not how I use the car these days. I would prefer better shifting over extreme use protection. There is no 'extreme use' for the car. Saying it's driven 50 miles a month is a 'pert damn near a huge exaggeration. When it is driven it is usually less than ten miles...occasionally 25-30...and only twice in decades of time have I driven it 100 miles in a day.
Browsed around it some today. Everything clutch-wise looks fine. No loose/bent/broken/oddly spaced fingers. Can't see all of the disc springs, but nothing looks out of place. Disc facing and spacer are fine...no missing pieces. Disc moves as expected when free...smooth, no up/down movement that might indicate a hub fracture/damage or pilot bushing problem.
Hear no noise when turning the trans with the starter (remote button...me under the car). Wouldn't expect to...the starter isn't exactly stealthy-quiet. Feel nothing rotating the trans from the prop shaft...but that has nothing to do with the input bearing.
Drained some fluid out. Saw a few (couple/several) gold-colored bits...but nothing shiny. Fluid level is full.
Throwout bearing, front bearing, broken input shaft retainer. No matter what it is the trans needs to come out, it will be readily apparent when that happens...
I would think 'readily apparent' would apply...but I'm not at all confident of that.
A BTW...but Passon's 833 book says the cluster shaft comes out before the input shaft. Is that correct? Why can't the cluster stay in place? The bearing won't clear the cluster? All the numbers say this is a 307 bearing transmission.
I sure don't want to fuss with the cluster. Arbor? Spacer? Got nunna that toolage. 76-bazillion rollers? Please...no!