I bought Marshall's Astro when he parted his car out. So far so good. I also have a WC T-5 and a 12-spline clutch that will be on the trailer for out of town events just in case.

I had a freshly rebuilt (professionally) T-5 break 3rd at Cresson last year after 5 sessions on track. My theory is that the case bearing bores get out of aligment and we don't check them for alignment before assembly. Then less than adequate tooth contact and boom, broken gears.