As far as differences between Chevrolet and G.M.C., my G.M.C. parts book lists a part number for the complete steering box assembly, while my Chevrolet parts book does not, however further research revealled that 41 - 46 Chev. and G.M.C. share the same steering shaft/ball nut assembly, so I will let you draw your own conclusions as to wheather or not they are interchangeable.
I swear I ran into a handful of different sizes when I rebuilt the box in my GMC COE. Those parts were not listed for my COE, but for different models. Maybe I was day dreaming...
If you need parts there are a few NOS suppliers listed in the links section. I got some of my replacement parts from them. And as far as price is concerned, I sold the steering column/box out of a '41 for about $50 condition unknown, but I believe it was in decent shape. Had I realized it, I would have measured its length as I have an identical unit out of a '41 1 1/2 ton truck.
Jeff
