Going by the cast, the Holley, Carter and Jegs all came out of the same mold. I looked at the Summit brand pump and it's also the same.
http://www.summitracing.com/parts/SUM-250020-1/
That doesn't mean all Carters and Holleys etc are from the same plant but these have to be.
Two more that are different from the above but just like each other are the Edelbrock and Mr. Gasket fuel pumps.
http://www.summitracing.com/parts/SU...1/?image=large
http://www.summitracing.com/parts/MRG-7716/?image=large