I have a pair of finned cast aluminum valve covers with the crossed flags emblem and all, but my question is why the numbers on the inside differ from GM part numbers of 474207 & 474208 that are most all of them. My numbers are P3965543 LH P3965544 RH The numbers are exactly like this on the underside of each valve cover including the RH and LH. Can anyone help?

 

Maybe they are off an older Vette? When I want to know what a part number is I call the GM dealer. They are pretty good about it. That's the only way I can think of to find out what they are.