1966-81 Chevy H/J Series

[junkmandan3]

WUF------As a little bit of history, we not only had tandem 2 speeds, but with Eaton axles , we had tandem 3 speeds. The 3 speed concept was an effort to compete with Roadranger transmissions, and was achieved by running 1 axle in low range, the other in high range and the ratio was equalized through the interaxle diff[ or power divider]. This concept came out in the early '60s, and worked OK except for occasional broken levers in the torsion spring assembly in the shift motor area. You had to be in low axle range in order to utilize the power divider to lock the axles together in slippery conditions. Keep in mind, on slippery conditions , unless the interaxle lock is activated, one out of 4 wheels can spin and the truck won't move. When you engage the differential lock , at least you have 1 wheel on each axle will spin . Nowdays many users will buy full locking diffs, where all 4 wheels are locked and will spin . The fleet I was in in the '60s had about 50 Fords and 50 Whites with tandem 3 speed axles. In '72, I worked for a Cleveland area grocery chain that had about 60 JI 9500 GMCs with the 6-71 and tandem 3 speed axles . I still remember a hotshot mechanic grabbing gears in the parking lot. It was a fast setup !