Run a can of Rislone Rear Main Seak Leak stopper through it.. you might be able to significantly delay the need to do that rear main and sump seals.. rear main seak leaks are often misdiagnosed as well, dont rush to do this unless you're 100% sure. The bottom of the bell housing does tend to collect oil from other, less expensive, leaks.
Are there any downsides to doing this? I've been noticing very slight leaking near my transfer case and wondered if something like this would help.