This guide I wrote for an auction site should cover more of your questions:
Case: On the inside of the caseback will be found the Vacheron & Constantin name and logo, the Maltese Cross. On earlier models (pre-1950's) there will be a six digit case number. Later models will also have a 4 digit reference number, and rarely an additional hyphenated number is added for special versions. The last three digits of the case number are often repeated on the inside rim of the case body, confirming that the caseback is original to the watch. Most Vacheron & Constantin cases are of precious metals. During WWII, more steel or steel and gold models were produced.
Dial: Dials are the most frequently modified part of a vintage watch. A repainted Vacheron & Constantin dial can be identified by the lack of an accent above the second "e" in Geneve, also sometimes misspelled "Geneva", and/or missing "SWISS" (early) or "SWISS MADE" (later) under the 6 o'clock position, and/or a missing "&" ampersand in Vacheron & Constantin (pre-1974). Due to the extremely fine printing, these features are often not duplicated on repainted dials. Other signs are crudely replated metallic finishes and improperly applied index markers. A fresh dial on a vintage watch should always require further investigation.
Movement: Vintage Vacheron & Constantin movements after 1938 were sourced from Jaeger LeCoultre raw ebauches, then modified, decorated and given Vacheron calibre designations. A six digit movement number will be stamped on the base plate, often with the Vacheron & Constantin logo. Early chronographs featured Valjoux base movements. The caliber number will also be stamped and decorated in gold. The finish of vintage Vacheron & Constantin movements is outstanding and clearly seperates them from lesser manufacturers. Both the case and movement numbers are recorded in Vacheron's archives and can be confirmed by contacting the Heritage Department through their website, but be prepared to wait. It is with movements that the greatest chances for frankenstein modifications occurs. Carefully examine wear to screws and bridges to see if the movement was dissassembled. Check consistency of finish and alignment of Geneva stripes between parts to ensure they were assembled and finished together. Fine regulators are often broken so compare the movement you are considering with other photos found on the internet to confirm all features are present.
Strap/Buckle: Vacheron did not adopt the Maltese Cross buckle until the late 1980's. A traditional square buckle was used prior to this and is more desirable if still present. Another frequently replaced item is the strap. A genuine Vacheron replacement is preferred but often not available. Both the buckle and strap are considered maintenance items that do not diminish value, however, the presence of original items can enhance collector's value.
Papers: Original papers are in French. A Certificate of Guarantee accompanied the watch when new and lists the case and movement numbers, jewel count, date of purchase and type of metal. A Certificate of Authenticity can be obtained for a vintage watch when the original certificate has been lost. The process involves sending the watch to the Vacheron factory, unlike Patek's Extract from the Archives, but provides absolute proof of genuineness. Details can be found on the Vacheron website.
LeCoultre Myth: During the 1950's, Vacheron was marketed in the United States by Wittnauer, which also distributed LeCoultre. Due to US import laws, they were required to have importation marks stamped on the movements of these "non-American" watches, thus the letters VXN appear on both Vacheron and LeCoultre movements imported into the United States. This does not mean they are the same! However, for a brief time this relationship was advanced by Wittnauer to enhance sales of LeCoultre and is now used by sellers for the same purpose. An examination of the movement caliber and finish is all that is required to highlight the difference.
There are several internet watch forums where you can learn more about the fine points of vintage Vacheron & Constantin wristwatches. Due to the small production numbers and hand-built nature of the brand, there are always oddities and exceptions to these general rules. While this makes vintage Vacheron an exciting brand to collect, it does require extra dilligence and research to avoid mistakes. Remember, patience is a watch collector's best friend.
thanks for the usefull information. I failed to find some pages with images showing differences. I.e. the bezel, knob,dial and markers.
Current replicas have all the details however there should be minor differences I suppose..