Correct way to measure splined shaft

[RLDSL]

does anyone know the official correct way to go about measuring a splined shaft?
I'm going to ditch the factory steering column and rig a tilt/telescoping one in out of a freightliner , and am having a heck of a time figuring out exactly what the size of the splined shaft on this thing is so I can match up an adapter double ujoint to hook it up to my borgeson steering shaft. I may just end up grinding it down to a square D but i'd like to use the splines on it if possible
The splines are regular pointed splines common to steering shafts
Thanks---Robert

 

[OLDBULL8]

Robert;
It will have a pitch circle, addendum, dedendum, tooth depth (includes clearance below the base circle) as well as pressure angle, clearance/back-lash etc. It may have teeth with parallel or radial teeth or teeth with involute or other forms or profiles. ***

 

[typ4]

Robert;
It will have a pitch circle, addendum, dedendum, tooth depth (includes clearance below the base circle) as well as pressure angle, clearance/back-lash etc. It may have teeth with parallel or radial teeth or teeth with involute or other forms or profiles. ***

That was so helpful

just count the input splines, 3/4x 36 rings a bell for some reason.

 

[mobilemech]

Russ is correct, measure the shaft (uncut ) then count the splines