Full Floating Rear Axle Housing

Hi,
I have an 03 Dodge Ram 4×4 4.7 V8 manual 5 speed with 148,000 miles. I bought it new with 6 miles on it. A year ago I had it in for regular service and my mechanic suggested (this is from my invoice): "AXLE HOUSING – Remove & Replace- Full Floating Rear Axle, Rear Axle" estimated at $2,400. Why would I remove and replace an axle housing? There is no indication of a problem that I am aware of (it does not leak and there are no weird noises) and I only rarely haul anything let alone anything heavy. Thank you!

My car has 148000 miles.
My car has a manual transmission.

– Full Floating Rear Axle Housing