The change was made at engine 968: 027352. That means the 27352nd engine. They started in late 85, I guess. I don't know where that engine number fell. Looking back at our shop history of 560SEL chassis numbers the earliest I found was in the 200000 range and was an 86. The first 27000 might have all been euro cars.
Bosch Master, ASE Master, L1
33 years MB technician