[Sandstone]

Preloading matters, it can ruin parts if you don't.

The service manual calls for putting in bolts, then lowering the vehicle so it's sitting on the wheels before tightening.

Next take a look at the pic and tell me if I am missing a cap and have a problem...(that on the top of the rear diff)

Looks like the rear differential vent, a rubber tube connects to it.

 

[Sandstone]

And btw, welcome!

 

[Sandstone]

The rubber tube is part of the vent tube assembly (#1 below), the other end is up around the fuel tank inlet.