T56 problems- clutch or trans?

Sounds to me like a stripped input gear. It happened to me once. But I suppose it could be a stripped 2nd gear. That happened to me too...... Or a broken shift fork. Yup, that happened to me too.......
In any case there's no getting around that the tranny needs to come down, and while it's out, you can inspect the clutch too, cuz you may have ripped the hub outta the disc; and yes that has happened to me too...I've been driving stick since 1969...so that's a lotta years to experience broken stuff.

If the engine was off and the tranny in neutral, and the clutch pedal up, while you were pushing it; and it was still noisy, I would guess the noise to be caused by something on the mainshaft, like a synchronizer assy or fork, cuz in this condition none of the geartrain is supposed to be moving.
But that doesn't explain how you were able to limp it back. That could only be explained by a clutch problem; like a finger failure. That has never happened to me.
So final guess, broken clutch.