Magnet

[Nostalgic]

It's a little late now and kind of a rough job to do upside down, but I drilled and tapped my new housings for a drain plug before I put installed them. I thought it was pretty stupid for them to cut costs by having you take out a bolt to drain - you can't peek in with a light or stick your finger in to feel for chunks or bigger shavings, and the bolt you remove to drain isn't all the way at the bottom anyway if I remember correctly.

Magnetic fill plug can grab enough to let you know general health, but if there's bigger chunks pre-failure, it might not catch them.