Would someone please put a Crow's 4x4 van on an alignment rack and report back the numbers? The other day I saw a picture of one of his vans where the radius arms were at least 15 deg off horizontal. That is downright scary steering geometry. Shouldn't even be on the road in my opinion.
Using the '05 up axles isn't just a matter of making brackets. There's a considerable amount of thought one must put in to the geometry of the whole system due to the fact that caster on a radius arm rig changes throughout the suspension travel. You have to get the best numbers for all factors involved to make the suspension work right.
That Pro-Comp radius arm is designed to be horizontal. Unless it has been modified, that van probably has Zero degrees or a few degrees of caster in the WRONG direction.
862k? What could go wrong? Why not chance it, it's only 20,000+ hard earned dollars!
Actually, doesn't matter how long the engine lasts. With that kind of mileage they just start coming to pieces. We've had leaf springs (with no rust) break in half on older fleet vans, and these were 2wds that never left pavement.