Lube the splines...

Take two of the right size nuts and screw on the stud, tighten one against the other, then tighten the top nut screwing the stud into the housing until tight, then with two wrenches loosen top nut and remove both nuts.
 
Take two of the right size nuts and screw on the stud, tighten one against the other, then tighten the top nut screwing the stud into the housing until tight, then with two wrenches loosen top nut and remove both nuts.
Use regular size nuts, not the coupling nuts, waste of money on coupling nuts.
 
Yeah, I bought a gen 1 a few months back and did the splines. They were bone dry and covered in that dried molly dust. Heck knows when they were last done. Luckily the splines were fine.
 
did you replace the 4 big bolts? they onetime use to my knowledge…