georgeszaslavsky
1580
the answer is so easy for me 5970 add to this the former ref 5004 and you have the two best patek chronos ever made, they both feature the ch 27-70q which is based on the lemania 2320 but
greatly and so well reworked , that I find better than Patek's new inhouse movement. And the lemania 2320 is still used by Breguet and Vacheron