I would suspect that it was just a matter of ease of production. Instead of having a dozen different wiring harnesses...... they just used the same one, varying by engine/trans options..... instead of having different versions for with/without 4WAL.

 

How do I know if I have 4wal?

 

Get a build sheet, stop at your local dealer today and give them the VIN.
It's free
I'm confident that you have RWAL only though.

 

I have the build sheet. I'll look at it but can I just check the rear hubs physically? I should look for wires? You ate saying that I might just have rear abs and not front? That's weird

 

OMG dude! Look at the freakin build sheet. I also say you ONLY have RWAL.

 

Only one wheel speed sensor in the rear. Right on top of the pumpkin.

 

I believe that plug goes into the window washer fluid terminal if I’m not mistaken, as for the axle breather tube, it’s smart to leave it how it was supposed to be stock.