2005 Ford F250 6x6 Powesrtroke Diesel

Chuck admits that the first tandem drive he built was a bear to get working right, partly because of the 32,000-pound load he tows-a Teton fifth-wheel trailer with triple slide-outs, one of which was modified with an extra door so he can keep his Harley in the living room (if you're getting the feeling that he has too much time on his hands, so did we).

"The power divider hasn't always worked so smoothly. When I started developing the box and drive system back in 1983, it took a bit of trial-and-error. I had to find the proper temper on the gears and output shafts, and the original roller bearings weren't strong enough," he says.

Chuck chose Timken tapered bearings that can be tightened up to take out any slop in the driveline, along with shims and spacers that allow some adjustability and fine-tuning.

He also discovered another component that wasn't up to the demands of this extreme application: "The Spicer yokes started to eat into the shafts after 10,000 to 15,000 miles, so I went to a tempered material."

Chuck's ingenuity came in handy when he found that there was a lubricating problem in the idler gear between the top and bottom of the power divider. He drilled three holes into the center of each gear, in between the teeth. This creates a vacuum when they spin, so they act like an oil pump.