Those links above don't discuss the SMB conversion too much. SMB 4x4 uses Dynatrac axles which are an aftermarket performance axle mostly used for rock crawling applications and performance 4x4 applications to get the most ground clearance and strength. They are Dana 60's and they put a warn hub on them.
cut and pasted from the dynatrac pro rock 60
-Unveiled in 2002, this 21st century design is still the benchmark for all other Hi-Pinion Dana 60's to try to keep up with.
-The ProRock 60 has a US Patent Pending. NO OTHER axle housing with a full diameter 9.75" ring gear can offer even close to the ground clearance of the ProRock 60.
-Even more ground clearance than a Dana 44!
-Unmatched Housing Rigidity to keep gears in proper mesh under extreme loads
The other unique feature is the transfer case SMB uses. They use the Atlas II transfer case which gives the van some unique options. You can put it in front wheel drive for the front digs or rear wheel drive (what I have it in for daily driving), and then four wheel drive Hi and low. This is built with offroad in mind.
The steering is federal mogul components (moog). The rest is Dana (spicer) parts for u-joints etc. The brakes and rotors are F-350 then they changed it to Ford F-450 in 2008. Standard leaf springs with upgraded Old Man Emu shocks which are again usually used for 4x4 applications.
Just some info about the SMB 4x4 conversion.