Broken Rb30 Box? Best Option

[trunk-rattlin]

I have a feeling i desroyed my box, managed to limp it home, I can get into all gears, but from a stop into first is some hardcore juddering and some knocking.

Clutch pedal feels a bit lighter aswell? Not to sure why that would be.

If i replace the box, i know the rb25det is the box to get, but its expensive over here. What other boxes can i use, are they all the same size? rb20det box fit my 30det?

Have an excedy 5 puck clutch in there too.