Question: Was your housing shortened and/or modified from its original form with new spring hangers, shock mounts, bearing ends, trailing arms, etc? The reason I ask is that it is common for folks to take a stock/straight housing and then weld all sorts of brackets to it (with a lot of welds on one side of the axle housing), then just go ahead and run it. What they don't realize is that the housing is warped and the bearings are not running true to the centerline of the axle - so now they are under a lot of stress that shouldn't be there - and they ultimately fail.
There are multiple ways to prevent/fix this - don't have the space to go into them here, but here are a few things to think about.
One thing to note is that usually you'll cut off the original bearing flanges when you shorten the rear. Then, if you're going to be welding on spring hangers, shock brackets, trailing arm brackets, etc.. - you do ALL of that BEFORE you weld the bearing ends back on. Then you straighten the housing (if it needs it - as it probably does), then you use a big-ole alignment bar to jig up the outer ends (with the pumpkin in - and bearing 'pucks' in place) - to ensure that everything is running off the same centerline --- then you weld the ends back on.
When everything is correctly done, the outer axle bearings should last for just about forever . . . if not, then you have issues.
Okay, enough coffee in me this AM, time to get back out in the shop! Working on some custom shock mounts for a vintage 32 hotrod roadster. Maybe I'll post some pics later . . .
B&S