Another FD data point.
Here is why you should not just replace the seal when a FD is leaking oil at the wheel hub:
Owner stated: "...1999 LT with 57,000 miles needs rebuilt as it is leaking oil..."
No history of metal flakes on the drain plug or in the FD lube. The inside of the drive was quite clean inspite of the outside being corroded from exposure to the elements.
With the crownwheel bearing in hand, it felt smooth, like a new bearing. No outward signs of damage or roughness on rotation as is felt when the races or balls are pitted.
After cutting the outer race off the bearing to better inspect the grooves at first glance everything looks fine. No pitting anywhere:
But on further inspection of the outer race groove it can be determined that there is a very sharp edge to the groove around a large portion of the circumference of the groove. My test for this is to scrape the back of a finger nail across the edge of the groove. In some areas the edge of the groove is very sharp and shaves the nail:
In other areas the edge of the groove is smooth:
I imagine that if I had an instrument that would profile the groove, it would show that the groove is wallowed out. This wallowing out of the groove causes a very slight wobble to the wheel resulting in leak at the seal.
I have posted this finding before. I post again here to inform the owner of the FD of my findings and for the edification of everyone else who might experience lube weeping at the wheel hub.
Conclusion: weeping of lube at the wheel hub, even in the absence of other findings such as metal flakes in the lube, most likely reflects an underlying bearing problem and just replacing the seal will not correct the problem.