Gears are the same, slightly stronger shafts but they still break pretty easy with 37's and are prone to bending at the flange with heavier rigs.

 

Whether it says rubicon on the box or not, all JK d44 gears are 'thick', and both the ring and pinion are larger than previous d44's. The part numbers may be different, but same gears. The box for my rear Sahara d44 gears says rubicon 5.38.

A little confusion there:
Non-rubicon front d30 = 27spline inner, 32 spline outer.
Rubicon front d44 = 30spline inner, 32spline outer

Non-rubicon rear d44 = 30spline
Rubicon rear d44 = 32spline

They use the same 32spline front outer shafts, which may be where some of the confusion comes from. I am actually using the 32spline outers from my d30 in the new pr44. (alloy inners and new joints, but re-used the stock d30 outers. Was limited on the cash, and needed to save what I could in order to regear the rear from 5.13 to match the fronts 5.38))

 

a lot of good advice..
just curious what did you end up with? or are you still looking?

I'm running a 3" Tereflex full flex kit with 34's... 285/75/17 which are about 3/4" smaller in dia and a little narrower then 35's 315/70/17's, i wouldn't go to 37's for a DD and a mild off road rig.
It's a DD and a off road machine.. I wheel hard, so I'm told.