Joe, are you still using bias ply tires? My '37 pickup was wandering badly also. I put on radials and almost all the wander went away. The radials made a world of difference.
BTW - Joe(6cylindersovertexas
)I just bought a steering box & shaft from a '41 pickup on ebay and plan to install it the same way you did. I will overhaul the box before installing it. Do you happen to still have the part numbers for the bushings and recirculating balls that I will need to overhaul the box?