I have been inspired by these threads. I am planning a big road trip to Alaska with my friends when I get out of the Army. I have a 2000 Astro van that I bought with low miles. However, it is only 2 wheel drive. I was thinking of converting to 4wd. I figured I would have to buy a donor awd to make this work though. I also will put a small lift on it as T-Low did his, and definitely contemplating the pop-top (basically copying off you guys). Do you have any better ideas on the conversion to 4 wheel drive?
I'm glad to have inspired someone else in the same way that I was inspired.
Pay a visit to the Astro nuts over at astrosafarivans.org for all the info, but the short version is this: In order to swap a 2WD Astro/Safari to AWD requires a complete front subframe from the donor AWD van. The whole front suspension is completely different (torsion bars instead of coils, etc.). I'm not clear on all the details, but there may be some welding of stuff required also (although I may be confusing with the pre-95 to post-95 front-end conversion...).
In general, the consensus is that it is VASTLY simpler/easier/cheaper to start with an AWD van unless there is a very compelling reason such as a camper conversion, etc. that has already been done on the 2wd van. They are more rare than the 2WD vans, but AWD vans are not strictly "rare". I setup a permanent region-wide craigslist search for AWD Astro and Safari vans (using crazedlist) and I get a couple of pops a week, at least.
The pop-top is probably best left to GTRV unless you want a hell of a project. (About a year later I still haven't re-installed my headliner, etc. while I sort out little details.) OTOH, it isn't cheap and I think they've recently raised prices. I can say though that it is BY FAR the most valuable part of my conversion in terms of usability of the van for camping. Being able to stand up to put on your pants and have some livable space inside the van is HUGE.
I built my van to sleep 3-4 people since we have a kid, but if you're just 1 or 2, it may not be strictly necessary to have a pop-up. Finding an AWD hi-top conversion van would give you some of the same improvements in headroom without the higher cost if you're only going to sleep 2 people.