It may have been put together with parts. However, I purchased a 2 barrel set that had that barrel and also a 12ga Tracker II barrel, came with a soft case, similar to the ones offered with the Versa Pak that is no longer made. Mine was about the same year as yours, don't remember the exact year. I did some research with H&R and the best I could come up with, it was a Special Order for Gander Mountain or possibly a supplier like Bill Hicks or SportsSouth. My set was new from Gander.
I know that when they fit Accessory Barrels at the factory, they will etch the serial number on the side of the barrel lug. Can't remember for sure, but I think they use the last 4 numbers or the serial number. I have checked on a couple that I bought new and they did not have the serial on the barrel lug. Hope this helped you out.
If you find that the 24" barrel is longer than you would like for a truck gun, you could always send it in for a 22" youth 12ga barrel. I think they still sell those through the Barrel Acc. program. I have one, they are really nice for walkin' around. Or, for more versatility you could have it shortened and tapped for choke tubes by a gunsmith for about the same price as a fitted barrel from the factory. My idea, if I ever have spare $$$ again, is to send mine off for a chop job to about 18 1/2" and a PolyChoke installed.
cookiemann