Beaver Bob, here is the parts manual break down of the '37 box,
http://chevy.oldcarmanualproject.com/parts/1929_54/396.htm . The box is a Saginaw built box, used in the '37-'38 and maybe '39 trucks, and the '37-'38 Master cars. They are simple gear on gear boxes, with a few bushings and bearings inside. 16-1 gear ratio so the effort is quite high to steer them at slower speeds. With new sector gear, bushings, and bearings, you can make them very tight and drive nice.
Sron48, you gear box Is a Saginaw built box as well, I doubt you will find a part number, possibly casting numbers but thats about it. 1941 through '46 gear boxes are similar in design, but the '41 box uses a different count of roller balls and a different diameter, so be careful when ordering parts. Measure the diameters, '41 use 1/4" diameter balls, the '42-'46 is a 9/32" ball diameter, the worm shaft and ball guides cannot be interchanged. Look close at the bottom bearing and race on the worm shaft, this is where water collects. If the race is bad, which is part of the worm shaft, you will need to replace the whole worm shaft assembly, which is the whole steering shaft. The bearings are barrel shaped, not a common bearing to find local, so truck part venders are your only source, I looked for a long time and never did find any.
Which ever box you have, follow the repair manual already linked for adjustment procedures, as all boxes adjust the same way.
