need to know lift, springs, shocks.
if you are getting the shafts built, lose the center bearing.
go with marlins extended front drive shaft slip joint.
reverse the front part so the grease plug for the slip joint is near the transfer case.
go with the thickest tube the shop will do for you.
I got .143 or.134, stock is less then half that and will bend. the tube is about 2 times as much but only adds 40.00 or so to the whole drive shaft. I just droped off my bent one at inland truck for retube and balance and the total was 160.00 they didn't replace the ujoints as it was only 6 months old. I got hung on a rock, backed up, fell onto the drive shaft and spun a spiral dent into it. that was .084 tube.
I sugest marlins extended slip joint in the front, I had 1 inch at full drop and on a water fall I hit the brakes and it still pulled out. I was not under power so no damage. just unbolting on a 100 degree water fall under a 210 degree motor. pain in the butt. nice bald spot from when I bumped my head on the header. winch locked to a tree to keep the truck from moving and the truck was at about a 50 degree angle. hanging on the front tires and sitting on the back tires and the tube bumper. that is after bobbing the bed 16 inchs. you get the picture.