A '41 gear box is the same design as the '42-'46, the recirculating ball diameter is different as well as the number of balls so not all parts interchange from '41 to the '42-'46. The recirculating ball assembly will not fit other year steering boxes.
The gear box itself is the same for all truck sizes except the COE, just the shaft length changes.
A good welder can shorten the shaft by removing a section, and I suppose a good machinist could cut a new threaded end.
I grafted a '37 end to a '41 gear box so I could use all '37 parts inside the cab. I cut and welded the two shafts.
One thing to look for on used boxes is the lower tapered bearing race on the worm shaft, it is not replaceable. If water gets in the gear box, it sets on the lower bearing.
