The hub difference sounds interesting; I don't recall any of mine having anywhere near that much of a "spacer" cast into the hub (including the SRW '65); you are saying the wheel mounting surface is 4.5" from the sheet metal brake drum center if I'm understanding you?
Here's a picture of the hubs on my truck (not a very good one, but the best I have)
http://i1067.photobucket.com/albums/u421/66Submarine/1963%20Chevrolet%20C-30%20dually/028hub.jpgI'll measure up the wheels I have when I get the chance and send you the measurements.
One thing to watch out for is the offset/width of the later wheels; I'm pretty sure they are all too wide to clear the leaf springs on one of these trucks with standard DRW hubs. The wheels I have on mine are already an extremely tight fit.
The 4.10 gears are nice; that's what both mine have in them. The no-spin should also be nice for off-pavement stuff.
I did look at my wheels and I do have some 28177's dated 1982, 28623 dated 1989, and 29361 dated 2007. I know I have tried the last 2 and they do not fit. I will try the 177 but it measures smaller diameter across than the 07 wheel.
The hub you have pics of looks a lot like mine but just a little different. Your center axle hub looks like it sticks out further than mine.
64 hub The 4.5" measurement was from my 70 1 ton that actually fits 16's. The 61-64 measurement is something like 2". This measurement is the distance from where the wheel bolts up at the studs back to where the brake drums flat vertical face is.
Also, I think the late wheel has less offset/backspacing than the earlier wheels but I will check that as well.
I appreciate you trying to help. Hopefully we can get this all figured out.
