Diff ID?

I searched and didn't really find anything regarding how to ID a diff. (Sorry if I overlooked it in my search). I do have the tag picture. It is stamped as WEB-BH 9EC 2 47 9 810C. I would say that makes it a 9in reach with a 2.47 gear ratio. But how will I know the spline count? Do I have to open it up? Also for a mix of track and street what gear ratio would you recommend? I was thinking like 3.7's or 3.89?

Thanks and I hope everyone is doing we ll and coping with this crap going around.

 

28 spline per this chart:
https://www.fordification.com/tech/rearends_ford05.htm

 

Thanks Beerbelly! That chart is exactly what I was looking for!

 

Exactly like mine. 2.47 open 9", 28-spline axles.