You should understand exactly what you are speaking about. Patek makes slight changes all the time which is why there are 1st, 2nd, 3rd series etc. Patek doesn't make mistakes in assembly as you suggested in earlier post. Their quality control is second to none! As for variances Patek used the second chrono hand with wider bottom beginning in 3rd series and have carried that through with other PC Chrono's. My 3970 was bought new and is a 3rd series and came with the second chrono hand. Again- before you start ranting and going on a tirade perhaps do a bit more homework.