I just got off the phone with Quadvan. The current cost for the base system is $12,500. The typical wait will vary, but is probably around 6-8 weeks. I could not pin the guy down on this latter point, but he said currently they have 13 conversions going at 3-4 days each.
At one time SMB did not have their own 4x4 conversion and used Quigley. Then after designing their own, for a while SMB offered both. In 2005 I had the option to go with either a Quigley or SMB. More than likely, that van is a Quigley and the owner opted for the transfer flow tank when SMB did the camper conversion.
2006 Ford 6.0PSD EB-50/E-PH SMB 4X4 Rock Crawler Trailer