Going by my own* observations; it appears that Pearl had the Slingerland style lugs up until the late 60's, possibly into the early 70s,(?) but also came out with the 'Battleship' lugs about 68, or 69, and produced them for a very short time into the early 70s when they were ultimately replaced by the now common, and widely copied, 70s/80s Pearl lugs. There are some catalogs floating around on the web if you dig, and I do believe that some show two styles of lugs within the same year. As these are Japanese stencil kits, unfortunately the prices/values are not great - based on quality, and demand. Some wraps and hardware styles are more popular, but there is the sentimental factor as well, and of course there is condition, and completeness. I've been looking for Battleship era, double tom mounting hardware for well over a year now - not easy to find and likely bring cost of restoring my kit up considerably. Matching orphans also requires much patience - what you've got there now ain't gonna amount to much, value wise, unless you're lucky enough to find someone looking for those particular shells, even then, it won't be much unfortunately. Nice looking drums though, good luck.