Vibration 45-50

I plan on rebuilding. Wanting a 2nd unit that is working to install, then rebuild this one.

It’s super rare that a trans causes vibration.
You can test that by simply pushing the clutch in.

If I was driving your car I could tell you exactly where the vibration is coming from, as I made a living diagnosing and fixing such problems for a large shop.

Diagnosing via description over text is almost impossible.

Driveshaft angle, there is a app to test that.

Trans in gear and clutch in while engine is at rpm.
Does the vibration go away?
If not it isn’t the trans.

But could be engine driveshaft or wheels and/or tires because they are all still spinning.

Vibration parked in neutral and clutch out with engine rev is engine or clutch assembly.

Parked in neutral with clutch pressed and rev is pretty much only engine balance or engine miss fire.

Vibration accelerating only and not decelerating, is usually driveshaft Ujoints or pinion related.
Same for decelerating only.

Vibration in the steering wheel, usually tires ot wheel related.

There is a diagnostic for most every possible symptom.
It’s a matter of knowing what it’s trying to tell you when, and under what conditions.