All that metal in the oil is not a myth ... the cones are wearing out because they are grinding away EVERY time the car turns ... spiders will weld themselves to the spider pinion when the cones bottom and you keep doing burnouts, it can even happen to a peg leg after 2 many one wheel burnouts.
I had a cone in the hot rod. The car didn't see too many burnouts but it would sometimes spin the tires when rolling, even on a hit above 50 mph. That's likely as hard on it as a burnout or more so.
One of the side gears stuck itself to the cross pin. That cross pin ate the differential assembly.
There were no outward signs of the failure. I only found it when I swapped diffs with the Imperial.
I went with a True Trac replacement.
