88 379 with 2 speed rear end

[5.9rookie]

Bought this truck at auction. This is a tandem with I believe 461 Eaton 2 speed. I’m sure these aren’t factory on 88 model. Nothing is hooked up to shifting motors. Looks like air went to the top and some kind of wiring harness plugged in on bottom. With nothing hooked up does it default to low or high ratio? Its got 433’s according to pinion shaft. All tags are missing. I have run air to top of both motors and no change. Any help appreciated.

 

[Truck Shop]

It could have come with/ordered with 461's. A very tough drive. Those had a diaphragm that can and will
rot through. Parts are available for the shift housings. Best thing to do is unbolt from housing and have
a look inside. 34 years old. Normally you will hear air coming out the vent, if it isn't plugged with dirt.

 

[525isx]

I ordered one in 88 with 402's. don't know why the wires would be used on 2-speed, on the side to side locker the wires control dash indicator lights

 

[5.9rookie]

Thanks men, I figured out 433s are my high side. I’m not going to fix motors.