I couldn't find any "off the shelf" parts to tighten up the third. There are 2 different thickness internal splinted clutches (0.080" and 0.082" HE) but because the clutches are bonded to the steels, there's not much you can do with the stack up. At least nothing I've found. (?)
There are different thickness input steels available, but you'd have to go the a 10pc. clutch pack to use them. Haven't got there yet on my build. I do plan to document that. There's also some special snap ring. I'm looking into that also.
The trans I built for my father in laws stock GTP had only the parts/mods listed, and it feels heaps better than any stock unit.
That hurts Bill.