1960 Aluminum Radiator Cap ID ?
I went shopping at Carlisle looking for correct radiator cap for my late July 1960 270 hp aluminum tank-top radiator. Confused as to which is actually correct, I was fortunate enough to find and buy two nice examples (see below, both are original, one is a "306" and one is a "362." I believe the 362 is NOS, the box is not for the cap.) The current 1958-1960 Judging Manual lists a "13-pound aluminum drop-valve AC cap #861362 containing "362" and "13# identification" (on page 44) as does the AIM (page L227). In the "Corvette Restoration Handbook" it calls out an AC 306 with 13# identification (page 175) for this application. My GM parts book (revised August 1, 1960) on page 209 lists an AC type RC-20 for this application, part number 861422 (no identifying markings or photos are listed). An AC Manual references the "306" for my late July 1960 car. I spent a lot of time talking at Carlisle and, although I'm happy with the deals, I spent some not insignificant money. Any help out there as to which is correct? Now that I have one of each, if I want the points just go with the Judging Manual? 
1960 Aluminum Radiator Cap .jpg1960 aluminum radiator cap for 270 hp (2).jpg
1960 Aluminum Radiator Cap .jpg1960 aluminum radiator cap for 270 hp (2).jpg