what should i expect to pay 8 3/4 chunk?

Actually, the big differences are the the pinion size/strength and the way pinion depth and bearing preload are set. You can put large or small u-joint yokes on any pinion. Basically the 741 has the smallest (1-3/8") pinion stem and uses shims for setup. The 742 is the 1-3/4" large stem that uses shims for pinion dpeth and a crush sleeve for bearing preload. The 489 is the largest (strongest) also know as the tapered stem (1-7/8") and setup same as the 742.