Rear end Pinion Bearings

How many pinion bearings are there in the differential. I was of the impression that there was one. Upon inquiry of the Auto parts store I was asked which one do i need the inner or the outer. I asked him if he is referring to the seal as the outer he said no there is an inner and outer pinion bearing and seal.

Pinion bearings consist of two tapered roller bearings, facing each other (cones pointed towards each other). The two bearings are preloaded by a crush sleeve between them, which is compressed by torquing the nut on the pinion flange to spec. The seal is located between the outer bearing and the pinion flange.

Does this explain the setup better?