i've had these manifolds for over 30 years....bought them at the Pomona Swap meet and was LIED to as to what they fit....was told 292-312."Y" block...well at least HALF lied to...as YES they are "Y" block, but are for the 302 (early version of the 317) that was used in the BIG JOB Trucks....there are 1963 date coded...and have the "upgraded" stress bar between between the two "horns"....picked up in the San Diego area....as might be a little expensive to ship...$300.00 firm....