From Tom Wood:
There are many different ways to build a drive shaft for the new JK. One method uses an adapter flange which bolts directly to the original pinion flange. This is really not much more than a round flat plate with bolt holes drilled into it and a conventional drive shaft weld yoke welded into the center. This then bolts to the stock pinion flanges. We just don't think this is as “clean” of a modification as can be done. What if the weld yoke portion breaks? You could have a tough time finding a new one or repairing the old one. There is also a concern with maintaining the accuracy of the part after welding.

In addition to this, the center of the universal joint gets pretty far away from the pinion bearing. Excessive overhung load is not a good thing. The above picture shows the stock flange on the left, ours on the right.

With our version, we’ve elected to make a replacement flange for the differential pinions. These flanges are machined from solid billet steel. We do not believe this flange will never break, We designed it to accept standard "off the shelf" mating flanges. If these flanges ever break, you at least stand a chance of getting a replacement part from almost any drive line shop. This also nets a longer drive shaft with the center of the universal joint closer to the pinion bearing.

We can build the either drive shaft in 1310 or 1350 series.

Unless you plan on beating the vehicle really hard, we believe the 1310 series front drive shaft would serve most people well. Likewise for the rear drive shaft.