Real difference in Holley fuel pumps

[Wizeguyrc]

I have a fairly new Holley "black" pump that has a cracked base. Last week I picked up a used Holley "blue" pump and planned on switching out the bases. After taking both pumps apart, I found the only difference in the pumps is the size of the hole behind the inlet and outlet ports.
They have the same size motor, fins, etc. To make sure, I borrowed a couple of other pumps, ( including a "red" one ), took them apart and they are all the same except for the hole size.
So that being said, if anyone is thinking about replacing their smaller Holley pump with a bigger unit, save your money, remove the base and drill out the hole.