Well, the Uplander didn't directly replace the Astro, but since the Astro was discontinued, along with the Venture, it has taken over the Chevrolet end of the mini-van market. Also, I've been under more Asto vans than I care to admit, I've never seen a full frame Astro/Safari, even the 4x4 models. The Astro, or M van to use GMs chassis designation, was not based on the S10 pickup, it has it's own unique chassis design. There's major differences in the steering linkeage, having 2 idler arms and a separate drag link, plus differences in the engine mounting, which is approximatly 4" to the right side of the chassis. There's also a corresponding offset to the rear axle center section. Now, I'll admit, I've never seen a 6 lug variant, must be a very late production ('05) and most likely, it shares the bolt pattern with the Trailblazer/Colorado, which is smaller than the std Chevy 6x5 1/2.
I tend to go along with the others. There's several '57s in my area running on mid-'70s 4x4 running gear, and if done correctly, they actually look stock. They don't really ride that bad if you leave the stock springs alone (no lifts) and will fit a 32x11.50x15 tire without any problems (floatation tires=better ride). You could find one pretty cheap, even up to the mid '80s would be ok, to. Find one with a rotten body.
No offence intended to anyone, but like I said, I've been under and have worked on alot of those vans.
