Finally got around to putting my car on ramps, mainly looking for breaking axles and shot front shocks, but only found one of the two. Luckily, it appears my axles have been rebuilt at some point, unfortunately, also not what I'm here for. I found a cap on the passenger side axle that doesn't seem to make any sense to me, and I'd really like to know what I should do about/with it.

It seems to slide down towards the transmission in a sort of failed seat, if that helps.