Hi Jim & thanks. Yes, that's what I thought on balance, but there does seem to be a few gaps.. i.e. were all records for 77/78 lost? Also i read that some 1970 drums had 7 digit, but I guess no way to know for sure, think I was just interested to see.1972 896xxx - 916xxx1976 917xxx - 1290xxx1978 xxxxxxx1979 xxxxxxx - 2013537
Be very careful using the online dating guide you quote above. It was developed by Rob Cook in 2003, using information he gathered and information shared by other drum enthusiasts. Much of the later Blue/Olive badge section is based upon information provided by Paolo Sburlati, but the source of Mr. Sburlati's dating information is questionable. Rob shared the raw information that he used to develop his table when I was developing my own serial number-based dating guide. I found what I believe to be at least one significant error, namely the 1976 date on a Sburlati set with serial numbers in the 917xxx range. This greatly impacts the table. None of the other online guides really address the 1970s and those that do all seem to just steal from Rob Cook's 2003 work. Therefore the same inaccuracies are repeated and perpetuated. Note: I am grateful to Rob and the others who developed the first dating guides, but by collecting much more information, an improved guide was possible.
Understand that there are not missing records for 1977/78, but rather no records at all from Ludwig relating serial numbers to years of production from the early 1960s through the 1970s. All of the dating guides that have been produced so far are based upon compilations of serial numbers and date stamps taken from drums which had both. The information is relatively available from late 1963 through 1971. Serial numbers started in late 1963 and date stamps stopped for Ludwig in the 1972 time frame. Any estimate for drums made from 1972 and newer are just estimates and less precise than in earlier years. There are some purchase dates reported from original owners which help to refine estimates for the later 1970s, but there is still a bit of flex to the numbers.
Your drums span a significant number of serial numbers, representing several years of production. Is the 15" tom a three or six ply shell? That might also help to date it.