"We chose to use the Factory inner CV's on this kit as after Quantitive analysis we found the inner to be a material close to a 4140 chromoly with a hint of Vanadium. We have used this type of end before with outstanding results after a special Temper and re-heat treat. "
considering the monster you're building, maybe getting hold of one of their prepped shafts would be good. Can't wait to see this run. ....G.