Originally Posted by photovdz
only little "problem" if it is one... the shutter makes a little noise after shutting on slow speed... is it normal ? My other M3 (741xxx) does not make that noise but it's a DS and not a SS...
Is there a place somewhere inside to find the original serial number of the donor body ?
Not exactly sure what you mean about the shutter, but there is a quiet wind-down buzz after the firing and completion of a show speed (below 15th of a second), which is normal for all M cameras (excepting the M5 and CL, which sound different). If your DS doesn't do this then it's time for a CLA. Also at a 15th and a 30th there should be a slight "spring bounce" after firing.
The original "L" seal was raised. This one does not look like that to me. As Tom indicated, a carved "L" seal can easily be faked.
Older M3s had the matching serial number engraved on the chassis under the film-guide plate. You might take a look there. However, the matching serial number engraving was discontinued in around 1960.