3 'splitters' or range selectors? Huh?

Its a 2 speed rear end & a 18 speed main box. Never go from hi to low until u stop. Low to high easy peasy. This truck is designed for off road driving.

 

That's what I thank it is. There is an AutoCar crane truck around here with that setup. It has an LL instead of an 18. Also has another flipper on the the dash for axle locks.

 

I used to drive a 1980 Mack with 15 speed and it had the deep reduction on the dash like that.
The truck also had a 380 cat in it.
Very odd set up for a Mack.
But it was built and purchased from Canada.

 

Blue splitter is also a 15 speed, red 13 speed, gray is an 18 speed.

 

Never shift 2 speed rears with the inter axle lock engaged.

 

Switch might not even be connected. My KW had the deep reduction on the dash from factory and the previous owner disconnected the lines from it and installed a modern 15 speed knob.

 

Yes.
Truck might of had a 15 speed from factory and someone put a 18 in it.

That switch on dash might not even be hooked up anymore.

 

I think you're probably correct. My two speed rear end switch looks different than the one pictured, and it is in an 89

 

That is the exact dash I have in my 2000 379 Pete, and that dash switch is for an Eaton 2 speed differential.

 

I have the same dash, but the 2 speed rears are on a switch similar to the air switches above the one in the picture, with a guard over it to prevent accidental use. Mine is in an 89 378 though, so evidently Eaton updated them.