The only markings that could be found on the entire Tub aside from the usual painted over Stickers were these Tac Signs:
So, correct me if i'm wrong, but it appears to be the former hauler for the DCO of 1 Service Battalion if I read it correctly. It did have dual Trays for what i'm assuming were 524's at some point judging by the holes.
One thing is for sure, it must have been the Battalion Beater at some point judging by the dents and dings.