I am a recent owner of a 1990, v6, automatic, with automatic hubs.

What's the procedure for shifting in and out of 4x4? Vehicle standing still? Do you have to back up to go back to into 2wd?

If someone could share the protocol I'd be very appreciative. Thanks.

In general, the procedure should be:

Stopped
Shift transmission into neutral
Shift transfer case into high or low range

To get out of 4x4, same process...

except, shift the transfer case into neutral.

As always, there are exceptions due to variations in transfer case styles and whether you have floor shift lever or dash mounted switch.

Regardless, the basic process is the same.

WRT to hubs, with manual locking hubs, it is a good idea to backup a few feet after unlocking the hubs to ensure the lock does fully disengage.

It is generally not an issue with auto-locking hubs.

My '89 owner's manual says...For 2H to 4H, Automatic transmission
1. If vehicle is moving, bring to complete stop.
2. Set the transfer case shift lever to the 4H position.

Thank you gentlemen.

Can you shift from 2H to 4H and back with the vehicle off?

Yes. I'd like to add that you can DISengage 4WD while moving, but to disengage the auto hubs you have to stop and back up about ten feet.

That is more of a vehicle specific issue. If you have a mechanical linkage, yes. Some vehicle (especially auto transmission) depend on a vacuum or electric impulse to accomplish the shifting.

Yes you can shift from 2h TO 4h with the vehicle off or on since it's a purely mechanical system for that drive change.

You can shift on the fly ONLY after stopping and engaging 4H, THEN with the vehicle in motion you can shift on the fly 4H<->2H with no problem THIS ONLY BETWEEN 2H AND 4H NOT 4L. You have to stop to shift to 4L.
To disengage, place on 2H and back up for about 6 feet.

Javy