Stuck in park..where is the shift interlock?

Not sure what category this would go in as it is not a "typical" model.

This is a Chevy Van 3500HD chasis that is actually a 32 foot Class C RV.

I suspect that the engine workings are pretty normal despite what it is I am hauling around.

The vehicle is stuck in park and I suspect it is the brake transmission shift interlock. My problem? I can't find it..........

Any help locating this thing would be VERY appreciated.....time to move my rig!!

thanks