Where are the vents on my rear axle assembly?

[scotts90ranger]

If the drum just got oil on it, it will clean up fine with some brake cleaner...

 

[Paisano]

Ok. That's what I thought. I have cleaned off the oil before with brake cleaner and a kitchen scouring pad, and it seems to clean up nicely.
The axle tube vent has always been open. I checked it more than once since I installed the complete rear axle assembly last summer.

I don't know for sure if the original seal was installed correctly. It looked like it was on straight.