2AMG: По первой ссылке, RO Jumbo, знаменитые часы. Читаем:
To my knowledge, there is only a single caliber that has been used by all members of the Swiss watchmaking trinity--Audemars Piguet, Patek Philippe, and Vacheron Constantin--and by no one else. Designed and manufactured (but not finished) by Jaeger LeCoultre as the caliber 920, JLC has, itself, never used the movement in a watch of its own. First available in 1967, the 920 is used to this day by Audemars (calibers 2120/2121/2122) and Vacheron (1120/1121/1122). Patek Philippe, while attempting to produce a reliable, flat automatic design of its own, introduced the Nautilus in 1970 with the 920 (Patek caliber 28-255), and kept the watch in production for 10 years (then switching to the caliber 335SC).

КОРОТКО - JLC произвел, но не использовал калибр 2121без отделки для AP, VC, PP.

По второй ссылке. Пока не ясно, но может и in-house. Но сколько таких часов производится. Единицы. Это так сказать, для того, что-бы БЫЛО.