XM861,XM863 & XM864 ???

[Bob H]

The following statement found on Change 4 of TM 9-2320-266-34 Direct Support and General Support Maintenance Manual an M880 series TM.

Distribution:
To be distributed in accordance with DA Form 12-38, Direct and General maintenance requirements
for Truck, 1¼-Ton, XM861, Ambulance XM 863 and XM864.

What are they?

off to search for info on these #'s now...................