Wondering how your using your tractor as I’ve got a 2006 2815 with 700 hours on it, not had any issues with mind. How many hours on yours? Are you running in 4WD most of the time on hard surface? I only use it when needing the extra traction and switch it back off. Also I run the Chevron 1000 fluid in transmission and front axle.
Where are you located?
Also not heard about a problem with the front axle on this model except yours as they were made by Mitsubishi for Mahindra.
How many hours are on the oil in the axle? Had it been changed before failure?
When one loads the fel and has insufficient rear
ballast, one tends to kick in the 4wd.
This puts a lot of strain on those smaller front ring and pinions within the 4wd system.
4wd is meant for tractive purposes primarily and not as an assist when the rears are light footed because of additional frontal load weight.
If you rear ballast your tractor properly for heavy fel loads, you'll get additional usage out of the 4wd.
I know it to be sacrosanct but heavy front loading and front wheel drive on a tractor is not really a good mix. Proper rear ballast is a much better solution.
Hardened gearing in this situation can relate to brittleness to the extent of snapping off teeth as opposed to increased wear with improper usage.