True: since 012 and the new w580 all autos come with 3:73. Their reasoning is that the autos has a full ratio lower first gear than the autos before.
When we had ours built in o12 a JKr auto I had them make it with 4:10, then it was 50$.
I would recommend you get 4:10. If you go up to 35"s you wont have to regear it. Unless you plan to tow a lot and have 35"s.