8.8

[Curious Hound]

Is it possible thats for the tube to allow expansion and contraction of gas with heating and cooling? I didn't see one in the pics. It's been a long time since I've worked on a rear so I'm not sure where exactly that would be.

That's usually over on the driver side tube. Barbed nipple for 1/4" or 5/16" hose. I think they're usually welded on.

 

[OldMan41]

Update...
This topic has my differential in the pic.

2010 Ford Ranger 8.8-Inch Axle vs 2004 8.8-Inch Axle - The Ranger Station

2010 Ford Ranger 8.8-Inch Axle vs 2004 8.8-Inch Axle - This page shows you the differences between these two axles.

www.therangerstation.com

 

[Curious Hound]

So, now you know you have a 2010 or 2011 Ranger axle. Mystery solved. I will note that @pjtoledo has been saying that AND he is the one who submitted the tech article you linked. Anyway, if that hole is drilled through and open to the inside, it needs to be plugged to keep oil in and contaminebts out.

 

[85_Ranger4x4]

Pop the cover to check for contaminants, drill/tap the hole to fit the closest pipe plug you can find, clean housing extremely well and button up with new oil?