I own two M101A1s and that axle is not stock. Just look at the lower axle ubolt perch - not military grade
For the bearings, pull a hub and measure both the inner and outer diameter of the spindle where the bearings sit. Very likely it's a standard size and you can order up new hubs.
New axles are pretty inexpensive too. I just paid $140 for a new 3500 lb Dexter axle, and just need to weld on the spring perches. A u bolt kit and the proper top plates for a 2" wide axle are $30 total.
Hubs are anywhere from $80 for both sides for idlers to $350 all-in for electric drum brake units with the parking brake feature.