Sure grip 7 1/4 strenght?

Darter6 said
Charrlie, We did the gear swap in a "67" 904 case and yes you have to change the front pump/input from a 68 up. Can't say about a 66 case for sure.

I think the 66 and 67 should be the same.

Hipo65 said
CharrlieS yer rite on the no-go gear swap, the splines on the output shaft are diffrent 'bummer'

That's what I found, when I tried to do the swap on my 65 trans, and you can't swap to the later output shaft, due to the rear pump, cable park assy, and flanged output. It might be able to be done with some machining, but I don't think it is worth it.