7260 big enough???

Moparman, as Clay's article pointed out the 489 case can have either a coarse spline yoke (early units) or a fine spline yoke (later units). There's an easy way to tell without taking it apart. See what size socket fits the yoke retaining nut. If it takes a 1-1/16" socket it's a coarse spline, if it takes a 1-3/16 or 1-1/4 socket it's a fine spline unit