Diff was leaking so I replaced the gasket. Still leaking. In my driveway overnight it leaked over a quart. It looks like the source of the leak is the drain plug but the oil level is at least one inch below the drain plug. The drain plug is tight. The only place the diff is wet (after I carefully cleaned it) is a line from the bottom of the drain plug tp the bottom of the diff then drips off. Crazy

 

Check the breather tube and make sure it is not plugged.

 

Check your pinion seal...

 

Try sealant on the fill plug threads?

I did rear about a possible bad AAM1150 casting once. Thin on the bottom, and scraped/rusted through. I don't think that's very common.

 

Yeah puddles forming under rear axle, thought it was pinion seal. Took to shop, seal dry, carrier rusted out leaking from bottom. Spent 6 hours, two trips to junkyard for replacement. 1st one had same rust thru, not discovered till at axle shop, so back for another one. Transferring axle from rented truck to mine was a chore with no lift. If shopping for one look outside rust belt! For me its two out of three axle carriers rotted out. Will try and post pictures later.

 

2nd jyard axle from Texas

1st Jyard painted axle

1st jyard axle bottom leak

Original Axle