what cone is this (D120-F content)

[pula58]

I am considering buying an old D120-F.

The code has the following numbers printed on it:

61827and

5197 MS/DW 9/18/87So, it looks to me like it was reconed 1987. But, What does the "61827" code mean?Do you think this is an actual D120-F recone,or was another kit used, like maybe the E120 JBL re-cone kit,or, some other cone. Thanks! P.