21 spline vs. 23 spline t-case input shaft

[4x4 Station Wagon]

Sorry if this has been covered before but I am looking for true experiences on a 23 spline vs. a 21 spline tcase. I am preparing to trade out my 21 spline coupler out of my trail gear doubler adapter for a 23 spline coupler so that when I do my gear drive doublers behind my r150 i dont neck down to a 21 spline where i need the beef the most. HOWEVER, common sense and lack of looking outside of the box would say that yes I agree that 23 spline is tougher than 21 spline but is the shaft any larger?? The reason I ask is that every issue "I" have seen is a twisted shaft right behind the splines on a newer non full length 21 spline case. I am not advocating that an earlier full spline 21 spline case is tougher than a newer 21 spline (even though I figure it is) but I am saying that they are the only ones "i" have seen broken and again it was the shaft never the splines..... I would appreciate true experienced advise as once I go 23 spline that becomes a special part at 167.00 minimum and I can buy an entire 21 spline tcase for 75! My last one was 20.... I want to ensure I am making a good choice. The 167.00 is fine if it indeed increases my odds of not breaking

Thanks.

EDIT: Sorry often times the question that comes up is what are your plans for the vehicle. Are you driving it back and forth to work or competing in the KOH. My answer is that it has 39.5 iroks with only 3 to 4 inches of lift, locked front and rear, and a 4.3 vortec. I run it like I stole it as it is nothing but an expensive toy. Hopefully that helps.

 

[GRM]

Firstly: 23 spline is a larger diameter than 21 spline.

My experience:

21 spline. Lasted 20k miles and 6 years in a single case configuration. Stripped out in 6k miles as a dual case.

23 spline. Currently at 8k miles with minor wear on the splines.

IMHO, 23 splines are necessary for a dual case adapter wherein the truck is driven on the road, but your probably fine if its a low mile (200 miles/year) trail rig.

 

[4x4 Station Wagon]

Firstly: 23 spline is a larger diameter than 21 spline. (Stripped out)

Perfect that is exactly what I was after. Thank you very much I will proceed with 23 spline

 

[Combat Chuck]

GRM nailed it, more splines means it was made with a bigger shaft.
Unless it's a GM transmission, then 10 splines is actually bigger than 35.