To be accurate 'C9AF-U' is not a 'part number'. Rather, its a (shorthand) identifying code by which the dealer can look up the real part number, using a crossreference. Quite literally, they can't order a 'C9AF-U carburetor'.

Is this a factory 428CJ holley (735 cfm)?

Sorry, but no. You have an over-the-counter service part sold to fit many applications, including various 428CID engines. It saw no use as a factory' carb, whatsoever.

If so is this the manual or automatic version?

As a non-stock service part it is really neither 'automatic' nor 'manual.' But it does have the integral bellcrank needed for use with an A/T kick-down rod.