I saw that Van for sale a while back. It looks to be in really nice condition. If I remember correctly it is also has very low mileage.
Not only is it a Pathfinder 4x4 conversion but it is also an xPlorer conversion van, part van, part camper...They were very cool back in the day (think of something like the Roadtrek of today)...They cut the floor and drop it down so its easier to stand up inside...The roof cap covers/removes the rear doors as well (a bad feature for a van IMHO) The roof A/C unit makes it too tall looking but all and all if someone wanted a very rare Old Dodge Van it is pretty cool.
Pathfinder Equipment Company closed in 1991 or 92 but I am not sure just what happened to them but the late 80s were the start of a bit of a recession so maybe that was the problem. The had at least two locations one in City of Industry ,CA and the others in Indiana?and ? (this was during the big Van Craze of the 70-80's so they grew fast) information about the company is a bit hard to find but they only did conversions much the way Quigley (which by the way started about the same time) does today, only brand new vans and they did not sell kits. At one point they were said to have been making up to 500 vans a month. They used made to order Dana Axles 44's for the most part and mostly NP (but later Borg) transfer cases adapted to the stock automatic transmissions. For the rear axle they just added lifting blocks to the stock springs and axles with new longer shocks or shock spacers and the OE shocks. They started with Ford (the Quadra Van) vans in 1973 at City Ford in LA and were doing Fords, Chevy's/GMC's (the K-Van, like the GM 4x4 trucks) and Dodges (the Vancharger) in their own facility by 1976. All of the Pathfinder conversions were built on One Ton Vans only. The Fords had Coil Springs and it was not a perfect mounting system as some people will tell you. I think the Dodges were also Coils but I don't know much about them. The GM vans used a frame insert and switched to leaf springs. I have had four of these (76-78-79 and 85) trough the years and they seem OK as long as they have good bushing and such, they are tough despite they all have Dana 44's. Those old uni-body vans (Fords until 1975- GM vans until 1996 and all of the Dodge vans until 2003 when they stopped building them were uni-body) are light compared to the full frame vans. Gordon the guy who runs Pathfinder-Vans.com is a good guy who can help you get some of the hard to find parts for those vans.
I hope that helps with your questions...