I suggest the wagon doesn't belong in the Bachmann box and that it's really an over-painted Dapol wagon. If you look at the unpainted seven-plank wagon on the Dapol website, you will see the overall structure of the wagon is identical. One possible source for over-painted Dapol wagons is Robbies Rolling Stock (see his site) though there are probably other suppliers who do similar work. If the original maker's marks have been mechanically or chemically burred off the underside of the chassis, it's almost certainly from an over-painter. I have several similar wagons in a variety of liveries that I picked up as a group purchase on eBay. Despite the livery differences, the interiors are the same shade of brown plastic with the same indications of internal wagon structure. You can find images of Robbies wagons on the web in purple Dapol boxes with his label over the Dapol wording. A bunch of his and others wagons are also shown on a Vectis Auctions site (image below).