Few points worth noting: Until 2005, there is NO Panerai in house movement. Technically all movements PRIOR were externally sourced. All these externally sourced movements, are subject to various degree of refinishing and re-assembly and then labeled with various in house codenames like OP XVI. There are, however, few models, which were marketed with their 'original' movements. These are mostly movements from new old stock or very limited supply. I believe Vendome Panerai made a few of these models during the early days to spark interest from serious collectors and have successfully done so .
So I believe OP XVI is indeed based on Lemania movement although highly refinished/personalized by Panerai.

