rear axel code 5 on a 57 ranchero

[Ranchero 57od22]

I have 2 57 ranchero's they both were made in K C Mo.in may of 57 they both had factory overdrive and a code 5 rear axel I am trying to talk to someone with the same setup to varify the original ratio .I want to keep it original.My email address is ranchero57 @southslope.net I am retired so I am around. Thank you I would like to hear from some 57 ranchero owners.