Quiqley has performed aftermarket 4WD conversions for more than 25 years. Now that GM is offering its Duramax diesel in the full-size G-van platform, Bowtie (and GMC) fans looking to combine all-terrain capability, diesel fuel economy and towing power, and up to 260 cubic feet of cargo room have a place to turn.
The basis of the conversion is the substitution of a Dana 60 front axle for the GM van's stock dual control arms, which is driven by a manually-shifted New Venture 261 transfer case. The stock corporate 14-bolt rear axle is swapped out for a Dana 70 unit. This is some serious undercarriage. It's also possible to get a conversion built using an independent front suspension, if the goal is better on-road foul weather traction rather than maximum off-road performance.
The conversion isn't cheap - a bit over $10K, plus the price of the van itself - but the total cost can be significantly less expensive than a typical full-size SUV, and we promise that there won't be a soccer mom in your neighborhood with anything like it.