well i have owned the car since 32K and i am at 156K. there is an inner stub shaft that is still in the tranny. i can feel it move slightly but can get it to come out. the GM8206 will not fit over the stub shaft. i will try the GM8048 someone mentioned here. is the inner stub shaft only on the passenger side you are saying?

Both sides have inner shafts, but just the one side is a short piece #675 the other side is a much longer shaft #678
https://cimg6.ibsrv.net/gimg/www.che...fa457e6af.jpeg

I have an auto 09 SS and i can confirm GM8048 axle does fit the driver side axle. the GM8206 one did not fit so maybe its for passenger side
i just put the GM8048 on, it seemed almost dead on for length, has a 36MM center bolt, and snapped up fine with the tranny. test drive still to come, doing control arm bushings, hub bearings, and brakes still!

Doesn't fit; how? Too many teeth, too few, diameter etc?

Only the passenger side comes out without disassembling the trans.

35mm 36mm is the wrench size, not the shaft size. Heavier duty nut may be larger wrench size and still fit the shaft.