is vintage crown for GMT 1675 different from modern service?

[g-boac]

I purchased a vintage Rolex 24-503 crown for a GMT-Master 1675 a while ago as a spare part. The crown and its original packaging are photographed below.

I have my 1675 in for service now, and it needs its crown replaced - its current crown is no longer water resistant when screwed down. The watchmaker servicing my watch (who is established in the Rolex community) raised concerns about the authenticity of the replacement crown I furnished. He apologized that he can't articulate specifics to me - just that is different from the modern service "monobloc" crowns he has. The biggest differences are:

1. My crown is brass core/stem, with steel crimped over it. Modern service monobloc crown is solid stainless steel, through and through.
2. My crown uses a flatter, thicker rubber gasket than the modern service crown.
3. The coronet differs slightly between the two.
4. The profile of the crown teeth differ very slightly, but generally the same.

For what it’s worth:

1. When fit to the watch, my replacement crown does fit and is water-resistant to spec.
2. I had the replacement crown evaluated hands-on by a second watchmaker, also established and experienced in the vintage Rolex community. He said it looks fine to him. I'm hoping to gather a slightly larger community opinion here to resolve the question both here, and for future reference.
3. Although a different watch, vintage crowns pre-1969 for Omega Speedmasters look quite different from modern service crowns, even though either will fit the watch.

I wanted to post photos here for a quick review, and get opinions. I have no issue with not using my spare vintage crown if non-genuine or aftermarket; but, I don’t want to erroneously retire a correct and genuine vintage part either.

The first photo shows my vintage crown and its original packaging. The second through fourth pictures show my crown side-by-side next to a modern service crown. In all photos, my crown is on the left; the service crown is on the right.

Thanks for your help and opinions!
24-503 crown 1.jpg

20150723_121721.jpg

20150723_121516-1.jpg

[nsumner]

To answer for immediate question,yes, they are different. As you stated the current mono block design was a complete revision.