My transmission has been loose from the engine for a while (missing one bolt) and has recently been lagging really bad under high load/ low speed conditions like launching or just driving normally from a stop. It's definitely not turbo lag. The clutch pedal engages/disengages right at the floor, which I attributed to a worn throwout fork/fulcrum ball.

Yesterday, right about when it normally goes from lagging bad to full power, there was a loud crack and WHIZZZZZ, followed by a clacking noise that matched engine RPM. I still had all 5 gears, still easy to shift, but it made horrible grinding noises if I accelerated at all. I was able to drive back home clacking loudly.

I dropped the tranny, expecting the clutch or flywheel to be chowder. Nothing. Tiny amounts of metal powder in the clutch housing and tranny fluid that look like normal wear. Everything else looks perfect, and if I spin the input shaft by hand & shift thru all gears, its smooth and doesn't make any noise.

So um.... what broke? Diff? Final drive gears? Which part of the tranny should I disassemble first? Thanks!