http://www.musclecarclub.com/musclecars/pontiac-catalina/pontiac-catalina-history.shtml should help you in decoding what belongs in your pontiac. also try Pontiac Historical Society. ( most pontiac lovers already know this though )

Sources: my brain. haha and www.musclecarclub.com

Location Of the Engine Code is stamped on right front side of block, just below the passenger head (on the block). You can find a list of Engine Codes here [url]http://www.oldride.com/library/1963_pontiac_grand_prix.html[/url]