I already have the 1350's I will be stepping up to 37" tires when these wear out and a Cummins some day. I'm ordering the PR44 and PR60 from Northridge and will be installing them myself then have a shop I trust do the aligning. Any idea on being able to tell if you driveshaft is too shaft?
If the angle of the driveshaft is too great, the driveshaft is fully collapsed (or the splines pull out) prior to suspension travel being complete, that is how you will know. You'll have to compress and flex the suspension through all angles it could see to verify this. As someone pointed out, since the pinion of the Dana 60 longer, the yoke will be closer to the transfer case. It'll also be a high-pinion if you buy a ProRock, so the pinion will be a few inches higher on a ProRock 60 than a regular Dana 44. I have a alldatadiy account, and it listed some general rules that apply to driveshafts:
Good cancellation of U-joint operating angles is within 1degree.
Operating angles less than 3 degrees (U-joint system).
Operating angles less than 10 degrees for constant velocity joint.
At least 1/2 of one degree continuous operating (propeller shaft) angle. On one U-joint system less than 1 1/2 degree operating angle.
With the driveshaft you have, it shouldn't be too short if it currently works on your setup. Make sure that the U-joint operates at a little bit of an angle though; the needle bearings won't rotate, grease won't distribute properly through the bearing and will wear out the U-joint quickly.
Here's more information on driveshafts:
http://www2.dana.com/pdf/J3311-1-HVTSS.PDF