Rear-End Gear Ratios

[marek4792]

So I just got the new differential put in and it rides like a dream at 55 bobtail ended up with a total cost of about 2800 including the core return. This involved taking out the wheel bearings and cleaning them along with the axle inside. Bearings were ok as the magnets caught most of the debris which ended up coming from the input shaft bearing and planetary gear bearings.

I wonder if it failed early at 1.2 million miles due to what the truck used to do as it was a former mega fleet truck from the Northwest pulling rocky mountain doubles and/or quad axle trailers before I got my hands on it and finished it off?