Hey Guys,
I've covered most of the issues on 2WD, 4WD, AWD, & Auto 4WD in previous posts about a year ago or so (just run a search on it to find those posts).
As some of you might recall, my solution to get the "best of both worlds" was to use a newer generation active auto-4WD t-case setup from a '99 up Jimmy that uses a NV-236 auto 4WD t-case (NP8 option) on my '93 4x4 S10 truck V8 conversion. This t-case has an active computer controlled module that interfaces with the later VCM's that the '98 up S10's & full size trucks use, and has a locked-in 2WD only mode, a locked-in 4WD Hi mode (this locks both the front & rear diffs together like any conventional 4WD t-case for off-road only conditions), a locked-in 4WD Lo mode (this also locks both the front & rear diffs together just like the 4WD Hi mode, but is geared down with a 2.72 gear ratio), and an auto 4WD mode that runs in 2WD until it senses rear wheel spin which causes it to pull-in the front output in order to regain traction (after traction is restored it disengages the front output and reverts back to 2WD...even under WOT). The 2WD only mode also disengages the front differential as well for better efficiency, but this does require the use of a standard shiftable S10 front differential.
