My 2001 F250 PSD tow rig has what you describe as well except you don't need the lug wrench to turn it. Looks like a normal 'manual' hub. when unlocked, they're automatic and you can SOTF. Otherwise you can get out, turn them like a manual hub, and lock them in for sure.

don't know how exactly this is accomplished, but i doubt its available for Isuzu.

-Rob

Robert Gorrell
1995.5 Isuzu Rodeo - SAS'd and SOA'd, sitting on 38x13 TSLs, spooled D60 front, 14bff rear locked by detriot, high steer w/ hydro, dual Isuzu tcases.