Rear-end vent?

[Bandit723]

Here is what you have been looking for on your rear bumper. Sure they are mini iPads Haha. Looks to be rivets.

 

[80Zcorn]

If the rear end is apart I would use a power washer to really blast any stuff out.

It's not I'll only open it's rear cover

 

[DougD]

If you're positive there's no venting at all, you can drill and tap the top of one tubes and install one there.

the hole is already there...unless it needs to be a different size.

Want to rethink the hole being there?

 

[accelo]

Some have the plastic piece directly on the differential and others a nipple for a hose. The newer the vehicle the more likely there is a hose to move the vent above any possible water line.
Sometimes the plastic piece will be on the end of the hose.

 

[80Zcorn]

It's a 79 and there's just an hole as seen on pictures