O.d.

The O/D are pretty tuff, and survive plenty of abuse, I believe the weakness was the small bearing surface used between the imput/output shafts. Even though they went to larger imput/output bearings, 308s, to help take up deflection in the shafts, the same small bearing joining the two shaft now has to take constant output shaft deflection/side-load plus turning faster than the imput shaft in High gear, as opposed to the two shafts locked in high gear, with no deflection .

The output shaft suffers, the "nub" bearing surface breaks down thru wear, as any bearing will.

With the extra H/P, the hemi had a bushed countershaft, that may be worth looking into if you have a countershaft failure.

I wouldn't hesitate to try it, with 3:09 low gear, rear gear selection and camshaft selection would be important considerations.

hope it helps . . cheers

Browse the B-body site, there's quite a few threads on O/D thrashing, and survival.