Tom If you have both sets of heads next to each other, they both will accept the 1963 valve cover and the six ways to keep the cover from leaking. They both even use the same set of gaskets with six liitle holes. I use the 452's on my 1963 413 and have since the summer of 2000. I also use the dual snorkle air cleaner housing of the same era and dual exhaust . We have a 1970 27 foot AirStream that we use behind our cars too. If there ever is a problem, I'll re-confer with MoPar Performance since they spoke to me with world knowledge that goes back to 1959 and the first 413's on their tech hot line ( 1-888-528-4364 ) when I did not know who to believe. Uncle Rodger & Aunt Gabby Colo Spgs ----------------- http://www.imperialclub.com ----------------- This message was sent to you by the Imperial Mailing List. Please reply to mailing-list@xxxxxxxxxxxxxxxx and your response will be shared with everyone. Private messages (and attachments) for the Administrators should be sent to webmaster@xxxxxxxxxxxxxxxx To UN-SUBSCRIBE, go to http://imperialclub.com/unsubscribe.htm