Had a similar situation, on a friend's unit, sorry I didn't think of this sooner.
Corrosion, on the brush plate, the rivet that grounds the brushes to the motor end plate caused high resistance and stopped the motor. Replaced the rivet, got the resistance to zero, and the motor worked fine . This may not be your problem but you could check it out and maybe carry the motor for a spare if it's repairable.
99DSDP 3884, Freightliner, XC, CAT 3126B, 300 HP /ALLISON 3060
2000 Caravan toad, Remco & Blue Ox.