Starting point:
99 Astro LE awd, towing package, g80 3.73, named Green Bean, or 6 Ball, can't decide yet.
The MO for this post. I'm still researching options in many areas, and I'm ignorant in others, so this is a "what if" as much as it is an "I'm gonna do THIS" build post.
Body: Lose the lower cladding and the bumper covers, replace the rusty upper dutch door and gas hatch and hood, mount a 3 rail commercial rack, mount school bus folding steps to rear dside and pside for rack access, remove rear seat and one captain's seat for cargo/tools/stuff I need in there. Gut the rear air (more later - see Engine section)
Engine: SyTy parts - exh mani's and xover pipe, cam (?), TD05-17 turbo, MAP sensor. Intake is still under research. SYTY is one option, stock cmpi, marine 4bbl mani (Holley used to make a nice one with great spots for welded injector bungs but I can't find it now) are other possibles. Exh will be 2.75 or 3" downpipe, Magnaflow cat and straight thru muffler. Upgraded radiator and elelctric fan setup to get rid of the shroud and free up turbo room. Water/air intercooler, using water/glycol chilled to damn cold with the a/c system rear a/c loop plus some bells and whistles. Propane fuelled IF I can find decent propane injectors and fuel pump and cure the purge before start thing. LIKE that 113 octane rating for propane and it makes for a very clean motor in the guts. Megasquirt3 fuel and spark control.
Driveline: built 4L60E with corvette servo, reinforced sun shell and the other hardware thingy, 26 years worth of lube mods, aftermarket tcm. NVG 176 goes away, and in goes NVG 242 (2hi, 4hiopen, 4hilocked, 4lolocked) with the Novak adapter. Rear axle stays for now, if it's strong enough. Now we come to the front axle. I'm a little leery of the aluminum case front diff. I don't like no locking hubs. I'm not totally opposed to ifs if I can get the hubs. SyTy cast iron front diff may be a possibilty, but rare. D44 high pinion is another route but a LOT of fab. Mitsubishi Montero front ifs is quite similar and very tough, with CAD AND locking hubs, and it has larger brakes with twin piston calipers. Rear montero axle has disks, and is as tough as a D60 at least. 4.625 ratio. If I go that low, I want an overdrive doubler between tranny and tcase. Much fatter sway bars with disconnects.
I have a set of 235/75/15's on it now, AT tread pattern, minor rubbing. Outwheeled a lifted Isuzu PU with them recently.
Comm and other electonics and power: Galaxy DX99 cb with a linear amp, Panasonic toughbook cf19 touchscreen on Ram mounts with a bluetooth gps bug, sine wave inverter (low watts), square wave inverter (1500w), CO2 tank system for compressed air. Two 7" round headlight sockets hacked into the front with Cibie H4 80w/100w conversions, original composite lights turned into flower planters with frosted glass, or headlight washer reservoirs, or portapotties or something actually useful.
Oh, yeah, the most important stuff. Fix the pside power window and cruise control.....