I'm not sure how they're going about it, but I've seen some GM 8-lug vans with Quigly 4wd conversions that looked like they retained the IFS setup... Like they're using the 2500 truck front end on the van. makes it a little taller, but if you are after 4wd without needing extreme capablilty, that might be an option too. If you're looking for an older van though, it's not very helpful.
![Frown :( :(](data:image/gif;base64,R0lGODlhAQABAIAAAAAAAP///yH5BAEAAAAALAAAAAABAAEAAAIBRAA7)
Good luck!!!