Make sure they know the difference between the center diff lock and the axle locks.
Agreed.
There are many reports where someone asked a seller if the truck was "locked" or "does it have lockers." Not wanting to sound stupid, they will usually reply yes. It is silly to ask most people this question as they really have no idea what you are looking for and, if you think about it, that is an unclear question.
We have had reports that people where responding to the Alarm Key fob as "lockers." (They lock the doors... correct.) Others responded that the door locks are "lockers." Those with the CDL switch as standard equipment (91-92) often refer to that as "lockers."
Unless it is a savvy seller, you need to:
1. Get the axle code from the white sticker inside the driver door. 294=Diff Lock Option, 292=No diff-lock option
2. Be sure the rotary diff-lock switch is in the dash.
3. Make sure the electronic diff lock mechanisms are on the axles.
4. Test before you plop down your money.
Several have reported the switch but no diff-lock option. Several have reported the Axle code, the switch, but no diff lock mechanisms (some PO did an axle swap.) And at least 1 guy had everything... axle code, rotary dash switch, diff lock mechanisms... but it wouldn't lock because some PO had the axle harnesses removed to the locking mechanisms. Non-US vehicles will have the 294 axle code but may or may not be locked.
Caveat Emptor.
-Mike-