Not to sound like an @ss, but if you don't have your gears in and have not used 4x4, then of course you will not break your D30 with 37s. You will start breaking stuff when it's in 4x4. My good wheelin buddy was breaking shafts with 32s on a locked D30 with the I6 in his cherokee.
I'm only posting to try to help you save your money. A 44 will require all new gears, locker and wheels plus you have a different bolt pattern, so you need to do something different in the rear (new shafts or spacers) to make it work. The 30 is a good way to get the solid axle in there, but is no stronger than the stock axle, and has no hubs meaning you break it-you fix it there or risk binding the yoke, breaking ball joints and losing a tire on the trail. This is true if you snap the ring or pinion as well.
It does Look good though, curious to see flex shots too.