Slip Yoke Splines?

I know the earlier t-cases had 21 splines and the later had 23 splines. I have a 90 w/ a 242 and my 91 has a 231. I was just wondering if the slip yoke splines were also 21 and 23? I'm just trying to figure out what the 90 is without pulling the case cause I have the driveshaft out of it and the slip yoke off the 90 slid right into my 91.

the OUTPUT slip yoke is all universal and i havent actually counted the splines on them. its the TRANSMISSION OUTPUT that changes from 21 to 23 spline.

ooooooooh ok i was confused about that one...and maybe a little hopefuly lol. thanks for the clearup.

slip yoke splines=27