Use the 88001 mechanism. At this point in the game, I really don't think anyone cares about exact dimensions, rather just having something that looks more generically American than the Marklin 8800 is a MAJOR WIN. A cow catcher instead of buffers, and black wheels instead of red is a HUGE step forward. A slope back tender is also an identifying mark, as are 3 domes instead of 2. Almost all American steam switchers have both a forward and a reverse sand dome on either side of the larger steam dome. I am not opposed to seeing a coal pusher tender either, as I like both the slope back or the coal pusher styles. And I can tell you this, if Marklin can sell thousands of what they call an F7 with bogus trucks, stretched body, and following absolutely NO actual dimensions, or MTL can print any roadname they want on that tiny east coast style caboose and unload them for decades as their only caboose offering, then, a Pseudo USRA 0-6-0 on their 8800 mechanism would also be a win win win. I win, something that is as close as I will ever see in my lifetime is made available, manufacturer wins, as people want them and will buy them even if they never build them just to have one in their collection, and Z Scale wins, as now Z Scale can finally say they have a USRA style 0-6-0 switcher that looks recognizable and appropriate for our steam era layouts.