Thats the same thing they told me at the driveshaft shop.
And the tube diameter wasn't able to support changing to the 1410...
So I had a new driveshaft made. It was a better, quicker, and faster way to go.
May be more costly, but now I have a new driveshaft, with new splines and all.
I should be able to sell my other driveshaft fairly easy, there are plenty of people out there doing rear Dana 60 swaps on Ramchargers. Since mine is already shortened, and has new joints and good splines it will be a simple swap for the next guy.