how to measure axles

[rtgreen]

let me explain.     i bought an 8 3/4 out of a 67 cornet. the housing and carrier were in the car. no axles. but i looked,and there were 3 ales in the car. one had twisted splines and the other two did not. one seems slightly longer than the other, but not by much. maybe 5 /16. how can i measure the axles correctly to go along with the charts i'm finding online?   from where to where?   

[Chryco Psycho]

Companies such as Mark Williams & strange have guide on measuring axles on their sites .
The floating pin in the carrier & the threaded adjuster will allow a little tolerance in length & still work ok .
You need to be sure if the axle has a sure grip that the thrust pins are in there if it is a 4 spider gear posi pre 70 also .