I have not been able to confirm or deny its existence. I think it's a later addition, but I have no definitive proof.

Honestly, I don't think I've seen what you have before, at least not in the past 20 years. It's an odd duck. Would be interesting to see what is marked on the insides of the case back and how the movement is branded. It is unusual to have Swiss hallmarks on the outside. Not all US-marked cases were ...

It's probably some period retailer, unless Raymond Weil was not founded until 1976.

"Weil" would be the retailer, usually a jeweler or a department store.

Without a Jaeger LeCoultre movement serial number, I can not precisely date it, but it would be from around 1954. You have a fairly rare 18k version of that reference (3155 to be precise). I have not had one in 18k recently, but in gold filled they're around $1000-1200, I'd imagine in 18k, it's doub...

That is an indication of how thick the gold is. The reason that put that, is so that unscrupulous people don't shave the case thickness in half and harvest the gold.

Where are you getting this serial number information and come up with 1953/54?

It definitely was a chrome-plated top case, with steel back originally.

However, I'm not convived that is an original case, to begin with. In my opinion, the movement and dial have been re-cased.

Can you post a picture of the back, insides as well if possible?

It looks like they polished off your chrome plate and completely ruined the profile of your case! ... and changed the crown!?

If the back has a serial number and a "B" on it, then the case top would have been chrome plated. Gold plated for a European market watch would be unusual.

Why would they plate it without your permission??