For my research into the production of the Hamilton grade 400 I need to know the serial number from the barrel bridge (Hxxxx) as well as the "hidden" 7-digit serial number that is on the pillar plate, under the dial. If you have any parts movements, please take a look for me. For a little more info about why I care, please see THIS POST

Thanks.

[The attached photo shows the under-dial serial number on number H2183. Not all have the "D MOD." notation]

I have a H1727, 21j

I'll check under the dial.

Lowell

Thanks, Lowell. Yours should have a different number under the dial.

.... also, if you can post a picture of the watch, or tell me what case style it has and what color gold, I would appreciate that info also. You can see the different case styles in THIS THREAD.

Sorry, no case.

What interchange of case will the 400 take?

Lowell

Judging from the serial number of yours, and the lack of case, it was probably originally in an 18K gold case in one of the four styles used. The only other appropriate case style would be an "Eton" gold-filled case. Although this style was also used on later watches, such as the grades 917 and 921, they are not the same size and would not even hold the movement without modification. One case that does appear to be the same size would be from another Illinois extra-thin movement (remember that the 400 is really an Illinois movement). I tried a 3rd model XT movement(Marquis Autocrat) and it fit a gr.400 case. Although a case from an Illinois may fit the 400 it still would not be an appropriate style. However, if you want to put it in a case to protect the movement and allow it to be used you might find an aftermarket case for one of these models. I would discourage parting out a complete watch just for an inappropriate case.

(P.S. - if you get under the dial of yours I would still like to know the hidden serial number)

Under dial # is 3,869,838

Thanks for the case advise. I've been looking for 20 years for a proper case.

Thanks, Lowell. For those wondering what I have compiled so far, following are the first-run grade 400s (H1001 to H1800) for which I have been able to record the hidden serial number:

Ham#.....hidden #
H1061.....4,018,497
H1403.....3,869,758
H1509.....3,869,655
H1701.....3,869,501
H1710.....3,869,510
H1727.....3,869,838
H1749.....3,869,830

The only two that appear to have any relationship to the Hamilton number are H1701 and H1710 -- the others appear random. The hidden numbers are Illinois serial numbers for grade 528 movements from which these were converted. I have recorded more first-run gr.400s, but do not yet have the hidden numbers. [The second-run grade 400s - H2001 to H3500 - appear to match the last four digits of the hidden serial number].