Express AWD center diff lock - possible?

Well as good as the AWD system is in the Express van and it has impressed me more than once, I have been bested by a scree pile.
The scree was deposited there by avalanches last winter at my ski hill.

I wonder if a center diff lock would have helped?

I am a newbie to the AWD system but hear the Landcruiser crowd extolling the virtues of their center diff lock as a good improvement over the open center diff.

Is it even possible to get a diff lock in our transfer cases?
I know I could go the part time 4x4 TC, but I don't really want to go that route.

Van at Norquay.jpg
Do you have the Borg Warner 4472 transfer case or the New Venture 136 transfer case?

You may not even have a center diff like you think you do, it might just be a computer controlled slipping clutch pack. Really no modifications you can do to the existing transfer case, only options to replace it.

As for trying to drive up piles like that, you really should have low range. Automatic transmissions have a torque convertor to get a little extra torque at low speeds, but at the expense of generating a lot of heat. Pulling away from a stop is no big deal, only a second or two of serious heat generation that is easily absorbed by the thermal mass of the fluid. But long hard pulls just keep the convertor loaded for almost the whole time, generating massive amounts of transmission heat. Low range replaces the heat generating torque multiplication of the torque convertor with actual gearing. This works the torque convertor a lot less, generates less heat, transmission runs cooler, stays happier, lasts longer. It is easier to drive as you are not winding the convertor up on every rock just to have the spring unwind and launch you as you overcome each rock. It will literally crawl over the rocks in a smooth and controlled fashion. Not lurching and crashing through them.
I think all the Express AWD vans have the Borg Warner.

I am pretty sure I don't have a center diff lock. At least not one I can control.

My question was, can I get one on my current TC.
The Landcruiser TC has a viscous coupling, like the Express AWD, but you can some how lock it if you want a fixed 50-50 split between front and rear axles.