Briefly lets go over axle widths, hubs, rotors, and drums.
The Eaton H-072 as found under my 1951 1 ton GMC measures 62-7/8" from Wheel Mounting surface to Wheel Mounting Surface. We'll call this a "WMS measurement" in the future; it is from hub to hub at the flat surface where the wheels bolt on, measured without the wheels in place.
I'm reasonably sure the dual wheel AD truck axle is the same width as the single wheel version. Discussion on that
Here The GM 14 bolt axle found under a Cab and Chassis (C&C) truck is often said to be 63 or 63.5" wide. Here are some pictures of these C&C axles:
PICTURE 1 and
PICTURE 2 I measured (with confidence) one at 62.75"
C&C WMS PICTURE The 1973-1988 14 bolt C&C at ~63" WMS is a very nice match/replacement for the old Eaton axle in the AD 1 ton trucks also with ~63" WMS
GM made a revised version of the 14 bolt starting in 1989 and later further revised it and still made today by AAM. It can be confusing but there is a lot of info on the 14 bolt here as well as by searching the net.
http://www.pirate4x4.com/tech/billavista/14b_bible/The C&C 14 bolt has the narrowest WMS available. Other widths of 14 bolt axle do exist. Van axles are quite wide (70"?) and not very well documented, lets ignore those. Single wheel truck 14 bolts are about 67.5" wide WMS. Not common but a dual wheel axle from a pickup truck (with pickup bed) is around 72" WMS.
Hubs,
The 14 bolt has 2 major hub types. (Other types exist where the rotor or drum slips over the hub. We will not go over these.. because of a shorter spindle I don't believe they are interchangeable with the other types )
The two major types are the dual wheel hub which makes the wheels sit in pretty narrow, the hub sticks out past the WMS 3.850"
Dual type hub PICTURE The single wheel hub makes an axle with wider WMS. The hub sticks out past the WMS 1.830"
Single type hub PICTURE The eaton axle hub can be swapped with some different bearings onto the 14 bolt axle spindle. Discussion and
details here The Eaton hub (only one hub for both dual and single) sticks out past the WMS 3.350"
PICTURE A 14 bolt single wheel axle can be made narrower by installing the dual type hub to achieve the very same WMS as a C&C axle, about 63". However the brake backing plates will be very close to the hub, they'd need to be relocated to fit drum brakes on this combination.
My calculations show the eaton hubs on a C&C or single wheel 14 bolt wold result in an axle about 64" WMS. Idelaly someone would do this swap and get real measurements because not 100% accurate to compare hubs like I did by how much sticks out. (It would be better to compare location of WMS to the back side of bearing inner race).
Finally drums and rotors, lets just cover how they fit and are attached to the hubs saving all the nit picky details for the next post.
The drums on the older 14 bolts are piloted to the hub (snug fit between bore in drum and hub OD) and then held on the back side of the hubs by the pressed in studs.
PICTURE Late model disc brake rotors and the original Eaton AD truck drums simply slide over the hub and studs same as, and just before, a wheel is installed.
They are also snugly piloted to the hub like the drums above are.
PICTURE late disc and
PICTURE Old Eaton drum both removed
