8-1/4" rear end questions?

I know that they have use the 8-1/4 for a long time, and I also remember that the number of spline has change in the late 80's, bu t I can't remeber wich year.
I will look for Dakota, Ram or Cherokee axle to try to find a better number then the 2.45 that I have.
But for that I would need to know, up to wich year I could reuse the gears in my 74 8-1/4"? How many spline there was in the earlier version?