Nick is right. The mule upgrade starter was a Prestolite. It also required the use of a starter solenoid, voltage regulator, and alternator. All MOPAR, same as M880 trucks. The wide wheels and tires were same as used on some trenching machines. Fenders were added for the use of wide tires. The upgrade was done at depot level for 18th Airborne Corps (101 ABN and 82 ABN). This upgrade was done primarily for the TOW system, although some were not fitted with TOWs. Many were used for cargo, along with the mules with the TOW equipped. Some were at forward refuel/rearm points for helicopters, hauling ammo. at artillery positions, and general infantry use. All models used by the Army, from the A3 - A5 were upgraded, mostly A5s. As far as I know the USMC never upgraded theirs. In the late 70's and early 80's, the 101 ABN, Division Maint. Wpns. Shop mounted some mini-guns to some mules for the 160 Special Ops. Aviation Reg. and 5th Special Forces Group. My dad was a wpns. mechanic and did the mounts.
From a collectors point of view, if you see a mule with wide wheels and no fenders, it's not correct. If you want a starter for a mule the new Bosh starters with the solenoid attached is the way to go. You don't need a separate voltage regulator or starter solenoid. Any single wire alternator will work to charge the battery.