the reason for the clip is to stop the cv assembly from moving back and forth on the spline. Is it absolutely necessary, probably not, there is only about a 1/2" of movement in the driveshaft, and the shaft cant come off without unbolting the u-joint on the other end. the few NP233s i've seen all with the CV shaft have had the spring clip.

 

Realized a few minutes ago that I might actually have a picture of my transfer cases' output shaft. I use a small digital camera to take a picture of every step when I am tearing things apart. Sure enough, on a pic that I took of the transfer case switch I can see plain as day the groove in the shaft. Add that to the list of stuff that the bonehead PO felt wasn't necessary or was just to lazy to take the time and do it right.

Now let me ask you this (and I do really appreciate you edumicating me), is there another groove inside the drive shaft input that the springclip clicks into when you slide the drive-shaft on? And/Or does the clip keep the drive-shaft input absolutely centered on the transfer output? The reason I ask this is because I have very slight miniscule amount of movement between the two shafts. I don't mean turning (of course) or in and out....I mean up and down/ side to side. It's probably less then an 1/8 inch of movement. In other words if I grab the drive-shaft right where it goes into the transfer and move back and forte I get tiniest little bit of movement.

 

i dont plan on reinstalling, im eventually going to bag the blazer after i do a engine swap,trans swap and change the rear axle (ive heard good things about dodge durango rear ends)