Upgrade time
 

So I have a 53 Wrx with a 5 speed manual gear box (ty754vn4aa) what are my options to replace / upgrade?

Unless at a standstill I've always had to match revs to get in to first and have to press the clutch a couple of times to get in to first or reverse from cold. Plus I get a whine when accelerating / decelerating. Gearbox and diff have had oil changed and made no difference.

And now when I turn left or right on throttle I get a clunking / metal to metal grinding noise as if something has broken off in the front diff and is getting chucked around or something is catching.

The gearbox is going to have to come off for an inspection.

If it could do with replacing what are my options for an upgrade?

Any other parts I need?

And any other bits worth doing at the same time?

I need retain 5x100 PCD as I don't want to buy new wheels as well.