Holley P/N 80457-2 3518
80457-2 is the part number and revision 2
It is a 600 CFM and the last four numbers are the date code. 351 would be in December and the 8 is the year which could be any decade between 1968 and 1998.
Your carb is the latest incarnation of one of Holley's best "all purpose" carbs - the 1850.
as was said it is a 600 cfm, vacuum secondary, usually with electric choke. It is a good carb for 289 - 351w in stock to performance trim (with the 351w limiting the rpm to around 6000 rpm). The 80457 does not have externally adjustable floats but uses the same jetting as the older 1850.
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