Truck Stop is a good place to look. They always have neat thing there.
Edit: After looking online, the only problems your going to run into is the threads not matching up, and that most shift ***** have the splitters built in. I dont know about the newer ones, but the ones I've driven were air-switches for the Hi-Low trans. speeds. If you got one that was electronic (I'm sure they're out there) you could possibly make it into a switch for something...