Anybody drive an air ride Rd mack??

I'm looking at one that is a 2001 that has air ride and I'm wondering how the rears lock.

Do the Mack trucks with the air ride have a separate switch that is fully locks the rear?

Did the factory dump trucks with Factory air ride all come from the factory with full lockers?

The person selling the truck tells me he locks the axles together and he hasn't had to be pulled out of anywhere off road, but he tells me he flips an inter axle switch, without using any other switches.

He's not sure whether it's inter axle or whether it's a full locking switch, but he only flips one and he says he's gotten out of everywhere he needed to.

Any information would be greatly appreciated, because I'd like to make sure before I purchase this truck that it does actually have full locking rears if that's the way it came from the factory.