I dug into a friend's 46rh today. The 165,000 mile truck is a recent low-buck purchase that would not move in any gear. No unusual sounds. He pulled the transmission, drained it, and did a thorough cleaning before bringing it over. He said the pan was full of thick nasty stuff.

The first thing I noticed is that there is a heavy varnish on everything. The second thing was that the fluid was not red. In fact, it looked about like relatively clean engine oil. The fluid in the servos was slightly pinker than the rest. The fluid does not smell burned.

After tearing it down, I found no broken parts. Nothing was burned. A few of the bearings are worn as was the thrust bearing for the rear planetary. All the friction surfaces look serviceable. The filter, however, was absolutely disgusting.
The bottom of the drums were caked with garbage. In fact, most things are caked with the stuff. There are signs of rust on many of the parts. The ends of the pinions for the planetary gears are especially nasty.

I did notice slight pitting on the gear and rotor for the pump. Those parts will be replaced.

He has had the converter rebuilt with an upgraded clutch and tighter pitch to better suit the stock Cummins.

Any idea what the culprit might have been? All I can think of is improper lube and a horribly clogged filter.

The fluid and varnish can be seen in this pic: