I did not read through this entire thred, but I will give my opinion and personal experience.
I ran 37s on a set of D44s (stock 01 TJ D44 rear with 30 spline Alloy USA shafts, 5.89 gears, spool, T&A cradle diff cover, carrier studs and nuts, and swapped in Rubi D44 front with 30 spline Alloy USA inner/outer/unit bearings with Yukon Super Joints, Detroit, 5.89 gears, Dynatrac diff cover). I ran 37-12.50-15 Maxxis Creepy Crawlers for about 3 years, and then 37-13.50-17 Mickey Thompson Comp Claws for about 3 years.
The front: I had no problems with the front for those 6 years, about 500 trails ranging from 3.5 to 5.0, and it is still running strong in a friends rig with 35s. I only had to change out the Yukon Super Joint caps once. Ball joints held up fine, axle tubes held up too.
The rear: Bit of a different story. It held up with the Maxxis Creepies fine. Once I went to 37" stickies is when I started have issues. In those 3 years, I blew up 2 sets of R&P, and grenaded 2 30 spline Alloy USA shafts. The last time I blew it up, I replaced the parts and built a D60.
So, my opinion would be.....with DOT 37" tires, yes, the D44s can handle them quite well. With 37" stickies, no way for a rear axle, even with 33 or 35 spline chromo shafts. The front should be fine with all the upgrades possible. But you need to go deep with the gears with 37s.
Flexes like a boneless hooker on muscle relaxers.