Confused with a Saginaw 800 Power Steering Box
 

I need some help with this. Back in 78 or 79 I ordered in a NOS GM steering box for my 70 Chevelle SS and stashed it away. Today I found it but have no idea now what they supplied me at the time. The cardboard box is shot and I cannot make out the original GM part number.
The steering box however has casting number 5691676 on it with a 174-1 date on the cover. It has three turns lock to lock which makes me think it is the correct variable ratio but what is throwing me is a CB in ink on the cover which all I can find is that crosses to a 77/78 Camaro z-28 with a 13:1-16 ratio.It is impossible for the date to be 1981 since the box was bought in late 70's.Was the CB code also used in any of the 70-72 GM models.
Thanks for the help
Joe