3rd gear crunch.

[Paul Burr <tigerpb@ids.net>]

I'll toss this one out to the collective wisdom of the list. Just this
past week, my TR6 has started making a slight grind on the 4-3 down
shift. It happens randomly, @ 1/3 of the time. The 2-3 upshift is fine. 
I drained and put fresh 90w into the tranny, but that made no
difference. OK, so what's up? Is the 3rd gear syncro shot? Or, has my
thrust washer challenged crakshaft finally worn so much that it's
causing this?