I have done both seals on my 99 4runner and 07 fj cruiser. The retainer on the axle has a bevel and in some trucks that bevel is too close to the axle seal allowing lube to get past it as the bearings wear. Buy a bearing from rock auto and new axle seal from toyota and have a shop do the work. Look for any bearing made in Japan. I think the BCA bearing is stamped japan, look at the pictures. Most are just rebranded but made from the same factory.

Here are two threads I started for the axle seal leak. The fj cruiser has the same setup as our 4runners.

If you want to do it yourself, you will still save money after buying all the parts and tools.
20 ton press harbor freight $180
Bearing removal tool on ebay $110
Bearings $60-$80
Seal $15
Fluids and misc items $100

You can see how close the actual seal lip rides near the bevel, top line in first picture. The second line is the dust lip mark. Flipping the retainer so the bevel faces outward solve the problem. It wont damage the seal when installing it this way either.

Rear Axle leak & bearing replacement | Toyota FJ Cruiser Forum


A possible solution to leaking axle seals