Just my 2 cents. I used to work as an overhaul mechanic when i was in the service on my latter years. The militarypurchased a certain amount of vehicles under contract. As time progress, the vehicle may need modification. An example the M101 trailer was originally desing to be pulled with a larger vehicle. Later they needed were modified and they became the M101A1. Later when the CUCV M1008 and 1009 came out the needed a trailer to be pulled with those vehicles, the trailer was modified again as M101A2. When the HUMVV came out then the M101A3. Some of this trailer were built new, but a great majority of them were converted as they came in to the DEPOT. No if the vehicle only go for a rebuilt, no modification, a tag is place indicating so. If the trailer was modify in any way shape or form the they were complete retaged as a new version, just like a new trailer. Just so you know the military only allowed $2,966.26 (lifetime) in modification and repairs for the M101 series trailers. If the modification and repairs exceeded that amount the trailer were schedule for disposition. At this point the M101 series is been completely phase-out in favor of completely newer trailer.