I was told the Aluminum Airlift Bumpers were for the Avenger ADA Trucks on M1097 chassis, they needed to be aluminum to meet weight restrictions or something like that. I'm pretty sure my 1994 M1097A1 truck has the aluminum airlift bumper on it, truck is still waiting on EUC. The truck was in controlled storage, I believe one of the 1300 Avenger trucks they built then put into storage during the GWOT due to manpower Big Army upgraded about 300 trucks a few years ago then released the rest for surplus. My truck has the instrument cluster, gear shift box assy and a few other small parts removed, there are still parts sealed with the aluminumized paper.
Another member told me the two square tubing brackets are for a bumper mounted work vise and the fold down step is affiliated with one of the Comm Shelters, the only experience I have with Comm Shelters was when I was assigned to a Military Intelligence Bn, was going to be 98G Russian Linguist, and the unit had AN/TRQ-37 Turkey 37 is what I heard them called, in a comm shelter on back of a brand new less than 50 miles M1008 Chevy CUCV. This would have been 1987-88 or so, the 550th MI Bn stationed at Sievers-Sandberg US Army Reserve Center on Route 130 in Gloucester County, north of the Dupont Plant the the NJ side of the Delaware Memorial Bridge.
I believe the Aluminum Airlift Bumper is NSN:
2540-01-196-4920, Part 12338218