8.75 Rear Axle

I'll need some help about the axle I have in one of my cars. I have a '56 Chrysler New Yorker and a '56 Chrysler Windsor and actually I am working in the conversion of the tapered axle rear brake, according to this link: www.crankshaftcoalition.com/wiki/Mopar_Tapered_Axle_Rear_Brake_Conversion. On this article they are talking about the 8.75 axle, which according to my "Chrysler, 1956 Service Manual" is the one that my New Yorker has. My doubt is that every article I have found on the web about the Mopar 8.75 axle, say the first of them were from 1957 cars. Is my "Service Manual" for the 1956 wrong about what axle I have in my car?
Author: mychrysler