My drums have not serial in that range - but since you perhaps have lot of info about Ludwig serial - you maybe know how this is possible?http://www.vintagedrumforum.com/showthread.php?t=41296
I did not address the second part of your post earlier.
You have described your drums as "3 ply rerings, clear interior, blue olive badge sharpen on two sides - but serial as they were 6 ply without rerings from 79." You indicate that the serial numbers are close together in the 1624XXX range.
I would suggest that the dating guide that identifies these as being from 1979 is incorrect. Based upon what I have seen, and to fit with the physical characteristics that you describe, I would think that they are more consistent with drums made in the 1976-77 time frame.
The Ludwig dating guides are fairly reliable for the Keystone badges, but not nearly as helpful for the B/O badge drums of the 1970s. That is one of the reasons that I starting gathering data. I wanted to see if I could contribute to improving the guides a bit.