Disconnected Wires hanging down at the rear differential on straight truck

You can have a 2 speed rear end or a heat sensor that leads to dash rear end temp. gauge?

 

Man, any time I've ever had folks pointing to my rear end because there was stuff hanging down, it was a bad day...

Kidding aside, it sounds like it may be the plug to the differential temperature gauge, if the truck has one.

 

Yes the Ele. motor sticking to the ft. of rear end that made the 2sp. shift from low to hi. had wires pluged in, a switch was on the shifter when it had 5sp. in it, follow wires to hi/lo. switch or put 12v to it till you make it switch back into hi. gear in rear/end?

 

You may have a 20 speed truck!

 

There's no reason why you couldnt use the high snd low ranges in the rear end. Usually on those old trucks they have a switch mounted to the gear shift. Tgey might have rerouted the existing line to the trans to run the high and low range there. You'll have to mount another switch and run lines to the rear end. Make sure it is a two speed rear end before doing all that work though. Btw imo 3000 rpm at 60 mph is a good way to scatter the engine all over the highway so i would look into this sooner rather than later.