9" Ford generally has axle seals installed before the axles go in. However, the bearings are sealed, and I've used the silicone method before with no oil seals. If you get a good coat of silicone, they usually don't leak. Did you weld after you installed the axles w/silicone? If so, the heat could have degraded it.

Currie sells a bearing with an o-ring around the outside diameter. It involves changing the bearings and spending som $$$, but it works. The picture doesn't show much, though.

http://www.currieenterprises.com/ces...e.aspx?id=1452

The retainer is what holds the axle in place. That's the standard setup.