Well, thanks for at least replying. I've also been asking around at Pirate and a few other places. Seems the general concensus is that the Toyota shaft is probably case hardened to a depth of 15 thousands.
Turns out it's not going to be an issue for me. OTT has told me that IF I can manage to break my new 32 spline 1.38" input (which they really doubt), they'll make and send me a new one for free.
I also did some more "testing" and the splines themselves do appear to still be hardened.......OTT said they didn't turn the diameter down at the splines at all before splining it, so the case hardening should still be present. My first "test" that was at the shaft's end (where they cut it off right before the clutch dog) and that part looked to be turned down significantly deeper so perhaps that's why it was so soft.
In any case, hopefully this info. will help someone else in the future. Hopefully Marlin will see this someday and post up. I know this question has come up a few times now on Pirate.
Thanks for the response.
Take care,
Sean
