GM changed the design of the 10-bolt in 1969. That's why the drawing in the 1968 service manual is different. Unless you have a bunch of 1969 10-bolts laying around, you might never see this version. The 1969 service manual also shows the older design.

There are two seals, two bearings and two axle housing designs for 1969. The roller bearing is for the later design and is about 1/16" wider than the ball bearing design. This requires the diferent seal set-up.

There is one reliable way to tell them apart: The bolts that hold on the ring gear are 7/16-20 threads instead of 3/8-24 threads.