I'm curious about this as well. My friend is doing a 35 1-1/2 ton and he wants to do the same. I can supply the measurements of the 35 Pins and End of the I-beam. if that would help.
I wonder though if he wouldn't be better off with the P-30 conversion (see tech tips) that would keep the axle rating a lot higher.
He's trying to keep this as simple as possible and was hoping that a later spindle would work on his axle. We can get the dimensions from his axle, but can't find a '50s 3/4 or 1 ton spindle to measure.
