Anybody know about 2 speed rears?

[k72516]

I'm looking at this awesome C-60... or C-65, I don't know what the models exactly were for the medium duty trucks... It's just one of those huge big square dually box trucks. 5 speed, with a 2 speed rear. But I never really got what the 2 speed rear was all about. All I know is that it's for when you have a really heavy load, you do something and it gears it down real low so you can get the load moving, at least I think that's what it's for.

Short version: What does a 2 speed rear do? And how does it work... do you just flip a switch to go between high and low? Do you think it would fetch any money if I wanted to swap it out, or is it just a worthless relic?

Also, is it true that they have four drum brakes or something? I read that on the only site I could find about 2 speed rears, but it was geared toward older pre 60's trucks, this ones a 70 or early 80 something.

[79BIG10]

I have drive a truck like that before. I think it was a 78? model delivery truck with a hydraulic bed to dump lumber. The rear end would shift back and forth from low to high ratios when you pulled on a cable on the tranny shifter. When you were carrying something very heavy and you were starting off you could start it a low gear and in low gear of the rear end. Then if needed you would pull the lever to shift the rear into a high to get more speed up with less RPM. Then we would shift into 2nd gear but lower back into gear with the rear end. The newer truck we had like that was electronically controlled but still same principal. I'm not sure how much they would go for as not needed as much on most trucks here.

[a28doc]

they were designed to give the 4 speed or 5 speed manual trannies double the gears ie: 1st thru 4th in low then 5th thru 8th in high. So when you were loaded it was easier on the clutch and tranny and gave better torque ratios.
Doc