Dan, if I'm reading this right, you're talking about the coupler in the rear, that hooks up to the tank carrying car. That's kind of a catch-22, if it could hook up like the rest of the train it would not have the auto release function. Agreed that the two Panzerjagerwagens are pretty much stand-alone models at this time, and it should be a fairly simple project for Trumpeter to come out with the flat car (tank not included, please). IMO, though, they will release the other cars first, as in a marketing sense they would be a more interesting subject.