fuel pump question

1954 ford mechanical fuel pump... ok??, checked Rock Auto.com they have 3 the least expencive of which is $35, the most expencive is $75. and I don't see anything that specifies that it's rebuilt or a remanufactured part, so here's the question... why the big price difference? anyone out there buy the cheaper one and regret it? any one buy the expencive one and have trouble. let me know.

 

Could be the expensive one has the vacuum pump on it? Many old Fords had one, to run the wipers.