SLIP YOKE QUESTION for 1970 C10

[1970DAVE10]

Changing out my u joints on my 1970 C10 drive shaft. In observing the slip yoke that slides on the end of the transmission, I noticed all the teeth were fine except for an entire row. The transmission teeth are all fine and don't appear to have any chips or issues, just usual wear.

Is this built this way? An entire tooth line (excuse my verbage) from front to back is missing on this thing. All the other teeth rows fine. I'm thinking it's supposed to be that way. Any help would be great. Started with doing the motor, this, that, and now I find this, it's like peeling an onion.

This is attached to a Saginaw 3 Speed. Thanks for the time in advance.