40k rears, Super B and BC mountains?

I've never had an axle issue running anywhere; oilfield/construction/pipeline (off-road, soft ground/mud), or coast-to-coast (Vancouver and Prince Rupert to NB), down to Houston, 120* in Arizona, etc. Lots of both, tri and Super-B. Lots of OS. I think they were all Super 40s, which I think are different, but I wouldn't hesitate. I'm sure you know; easy on the throttle, especially when loaded, uphill, low RPM, yadda, yadda, yadda...

I did blow up an 18-speed though.

 

I'm always confused with 40 vs super 40. I want to say super 40s are a 40k housing with beefier internals.

I seem to recall @uncleal13 gave some good advice about this exact question a while back.

 

So the Super 40 is built like a 46 but weighs less?

The only rears I’m familiar with is the regular 40 and 46.

Just a few weeks ago, I learned there are 52,000 rears under some trucks.

 

Does the super 40 have the same amount of oil as the 46...?

 

I did super B flat deck for a while with a 2006 Century Mercedes MBE4000 450 hp 18 spd, 4.11 gears in 40,000 lbs rears. The rear ends got hot, crazy hot. And this was in the winter pulling Rogers Pass and the Salmo Creston. Temperatures exceeded 300 degrees. I pegged the transmission gauge , it went to 350 degrees. The transmission cooler was air cooled, but it was mounted under the sleeper.
Later I switched to super B hopper bottom on the prairies. In the summer they would still push 300 degrees on the tough pulls. After two years the bearings gave out in the front diff.
The last couple of trucks had 46,000 lbs rears, temperatures rarely break 200 degrees. That would only happen on the hottest summer days, 170 being normal.