What is the spline count on a 4L65E output shaft and pinion gear spline count on a 10 bolt?

What series u-joints are stock on a 1/2 ton? 1310? 1330?

Also, does the part of the driveshaft that is attached to the diff (don't know it's real name) need to be changed when upgrading to stronger u-joints? And can that part be changed without tearing down the entire rear end (again)?

 

27 Spline one the trans. Not sure about the other stuff. Vince

 

Try looking at a '3r' series u-joint (inner lock). This is what I saw for my Tahoe and if I recall the table in the book at the driveline shop.......same as the 1/2 ton truck.