I broke some teeth of the pinion gear on an aftermarket 4.30 gear-set (D60).
I had previously over-heated the diff pulling this load (with 17 people in the van) up to Alta:
I think I only had about 20,000 miles on that gear-set.
The following big trip I loaded 4 snowmobiles into the trailer. This required launching them up the ramp and holding the brakes on landing, otherwise they couldn't make it up the ramp. Upon pulling away, it was evident something in the diff broke during this loading process. I drove a few miles a repair shop where the broken teeth were diagnosed. Diff was rebuilt with Dana 70 4.56 gears. My regular axle shop thinks the overheating weakened the diff, which they had previously voiced concerns over the loads I was pulling on the Dana 60 diff. 4.30 gears are even weaker compared to stock ratios.
This last October, I busted my carrier in half. At first I felt surging like the torque converter clutch wasn't staying locked. Then it sounded like wheel bearings went out, but after changing those to no avail, I brought it to the axle shop (Synder's in Albany, OR) where they found the busted carrier. They had not seen one bust in half before. It is a Ford Trac-Lock carrier offered as an option in the E450 motorhome package.
Still not sure if was a defective unit (which I doubt since it made it ~150,000 miles) or maybe I'm just putting too much power through it.
Important thing is I was still able to drive both times. About 300 miles after I busted the carrier.
We put another Trac-Lock carrier in, and a new gear-set since they were anodized from heat in the diff, but otherwise un-damaged. We'll see how it holds up this time. If it grenades again, I'll stuff a Dana 80 under it and upgrade the guts to a 12.25" gear-set. Or maybe just add a 2nd rear axle? The EB vans look pretty god with tandem axles IMO.