I've seen more or less filled in Classic lugs on the same drum. Some of the lugs were very hollow, while others were more filled in. This was on a late-sixties tom, and I believe the drum was all original. Even had old ludwig heads on it. It didn't look to have been tampered with in any way. Like other pieces of hardware, I think Ludwig changed lug molds a few times in the sixties and would use whatever stock they had available. My 1964 kit has very heavy, filled in lugs on it, while my '67 kit has lugs that are lighter, and less filled in. I also purchased a separate tom dating from 1964 at a later date, and it too has the very heavy filled in lugs. So, who knows for sure?