the part #'s and NSN's that were on the racks, were they on a hand written "fill in the blanks" tag or some sort of factory packaging info? If they were on tags, I bet you fell victim to the "Unmatched Recoverables" process in the supply system. For those that dont know, this is how Unmatched Recoverables work.
A unit needs a new starter for a humvee because they have one on a humvee that doesnt work. Shop office orders it. It comes in. When new starter is given to the mechanic, the mechanic is told "bring back the broken one" The computer shows that the unit has a new starter, (say price is $500 to make the math easy) The old broken starter is worth $200 for turn in so it can be fixed. So the final cost for the starter is only $300 to the unit IF they turn in the broken one. If they DONT, the unit gets charged the full cost. This system is desgined to punish BN's in the pocketbook who dont turn in recoverable parts. When the mechanic turns in the starter, it is taken off a list called the "Unmatched Recoverables" The list is a listing of all the parts that need to be turned in so they can be repaired or taken off the books to keep all the supply types happy so they know how many of X item are in the system. Starters, canvases, trannys, and engines are just a tiny part of some of the items that are on the list. Units have lots of vehicles and this list of items can grow quite huge, in both length and $$$. These sorts of stats get briefed to BN CDR's and higher. The BN CDR wants to keep this list as little as possible. Once a week, someone goes thru the list, and asks mechanics "where's the broken XYZ part so we can get it turned in?" Sometimes mechanics loose items, they canabalize broken engines to get some good parts off, ect. Once an item is on the list for over 30 days, the pressure is REALLY on to get the part turned in. At this point mechanics will do whatever they have to to beg, borrow, steal or flat out lie on the NSN/Part # the part to get it off the list and go home on time that day. On things like side racks that all look the same when they are strapped to a pallet, it's easy to tag the part as part #1234 when it is really part # 5678 the part gets turned in, and in this case of the side racks, they may find their way to DRMO and get GL'ed out, and you, the buyer gets screwed because all the info thats on the tag is what the unit SAYS it is. Obviously, some parts are hard to BS like starters and engines, but quite easy to do with a folded up mound of vehicle canvas or side racks. My guys often would order the wrong side rack, get it, figure out it is the wrong one, tag it as unserviceable, and it would go to DRMO. Not the right way to do it, but it did happen. It's easier to say that the part you got was broken than to admit you ordered the wrong part and spent $ needlessly because you cant read the USEABLE ON code.
Please note: This is a VERY simplified short explanation of how it works.