is closer to the roots. There is no "Blackseal' in Panerai history and the name has no significance (unless you call the pre-V era in the mid 1990's as 'history',,,,). The history of the Radiomir is the Ref. 3646, base, simple and clean. If you want to come closer yet, the limited PAM 232 offers you the original 47mm size and the solid caseback. (There are a few specimens of 3646 with a small seconds hand at 9/Angelus movement, but no doubt the the classic is a base)
Hope this helps,
Asi