I've read a lot of conflicting info regarding whether 3590.50 Speedmasters case serial should match the movement number. I've read people say with conviction that it should ALWAYS match and others claiming to be watchmakers who think they don't necessarily match until the late 90s. Most of these threads are a few years old. With the late 80s and early 90s tritium Speedmasters quickly becoming considered vintage and prices going up, I feel like the correct answer on this should be documented somewhere right?

This question is particularly acute for me because I'm considering the below watch and I think it may be a franken due to the mismatch. If not for the mismatch I'd think it a pretty decent early 90s 3590.50 with very pleasant tritium. What's the braintrust here think?

 

My belief is Omega would not put out a watch with two serial numbers that don’t match, unless it was a rare mistake. And they would fix it if it ever came back for service.

Any claims on the internet should be taken with a grain of salt.

including this one.

 

They should match.

 

Why wouldn't they match, because the whole reason for putting it on the outside is that it matches the inside.

 

Not sure who is saying they don’t have to match, but that is very wrong.

 

Thanks all. Makes sense to me that they should match or somehow be off by a very small number by rare human error during production. But Speedmasters are a strange animal with many peculiarities. Wanted to make sure where wasn't something I didn't know I didn't know, especially on these less meticulously documented 90s variants. A shame this is a franken, really like the patina