possible to tell np231 input spline w/ out removing t case?

i have 1989 jeep cherokee. np231 t-case w/ 26 spline rear output. the 4 whhel drive in my t case is shot. i can not how ever remove it to count splines since it is my dd. is there a way to tell t he input spline w/out removing it? so i can get a new one and therefor my jeep wont be held up in the shop until i can find one?

Your year should be a 21 spline input assuming it has the original transmission and t-case.

as far as i know it is original everything besides the 1.5" budget boost.