RE: The Wonderful World of Half-tracks!
I went ahead and ordered a pair of VS Tank Tiger gearboxes for myself and a club mate from [link=http://www.rctoybay.net/SearchResults.asp?Search=Engine&Search.x=14&Search.y=5]RcToyBay[/link], and a premium for the SINGLE Sdkfz. 251/22 with PAK 40 from [link=http://macsmilitarycollectables.com/Shop/]macsmilitarycollectables.com[/link], but it's exactly what I was looking for and don't mind really.
Now we just wait for parts and start the hunt for a front axle on the cheap that I can attach steering knuckles to. Not sure what I'm going to do exactly but I'll keep ya'll posted.
I think I'll pursue a custom Clark board... we'll see!