Pump companies made changes in their pump all the time. When a pump was introduced it might have the same base as the previous model, but when they ran out of them it would have a taller or shorter base. Yes, I relied on factory literature for pictures for my book, I didn't have the time or the resources to travel around the country and take pictures of pumps in personal collections.
When using my book, look at the picture with the thought in mind that they probably made changes in the pump but didn't bother to change the pictures they were using in their sales literature.
Author, Gas Pump Identfication books 1st & 2nd Editions & Air Meter Identification books
We rebuild ECO air meters and sell parts.