Well the Atlas II simply has a sensor on the T case. When the front stick is engaged the light comes on. It has nothing to do with the rear stick or the axles. If you do have an Atlas a 4x4 light would be easy to add.
You can see my light in this image. It's green and very bright. It is in the "stock" location for my van, a 2005. I would prefer it be somewhere else as it is not readily visible from the driver's seat, however it occupies what would otherwise be an unsightly hole so I've left it in place.
For the record my Quigley 4x4 (2008) has an orange light in that location. I used it last night and it is VERY bright when I'm driving these dark country roads in the rain. I'm thinking might be worth putting some secondary translucent cap over it to dim it down a bit.
Pueblo Gold Ford EB 350 v10 with EB 50 floor plan & Quigley 4x4 from Huntington (aka: Minerva)