I believe the difference between it and the JK one's are the new axles are more heavy duty in all areas. Ring gears and pinions are thicker along with a change in angles and how they are cut for added strength. The pumpkins and axle tubes are more reinforced/thicker. The front knuckles are much stronger. Etc.If that's true I think the dana 60's were around 5,500 so that could work. I'm thinking maybe the ring gear? Don't the M220 use the same spline count as the JK Rubi 32 spline? Maybe they changed the axle shaft material? I hope so it is one of the bigger things I worry about on the 392. My JK has a dana 60 that runs 35 spline shafts because I had issues keeping the dana 44 happy in it with 37's. twisted splines and locker failure but it does have a 4:1 transfer case in it and I have pushed it at times.
The idea behind this was to keep strength up to allow the use of more horsepower and/or tire size increase while keeping the physical size and weight down.
There has to be someone who cut one up to prove this.