Vile franken or quirky custom mod? (Speedmaster ref. 145.012)

So I am looking at a ref. 145.012. Reasonably affordable, but then again that is because there are no bids at present. That could mean no one is interested because it is a vile franken, or it's just early days. Anyway, it appears to have correct applied logo, 'Professional' printed on the dial, DON bazel, and an appropriate teardrop chrono hand. I am not literate on pushers and crown, so can't tell one way or another in that regard - but safe to presume they were replaced at some point(!?).



Comes with an extract:


Faded bazel to blue (DON) that I happen to find attractive:


And then the shocker! This caseback on a watch delivered in '68:


So for a noob, with shallow pockets. What do you think of the idea of purchasing this watch, and perhaps putting a sapphire caseback on it to show off the 321 movement, and to replace what I presume is a despicable impostor?

Help me out, what gives it away?

EDIT - OMG! - the applied logo for one.
EDIT2 - The bloody DON! I thought it was the lighting and didn't double check the details.

Better ask whats going on..

I just did. Asked for pics of case-back and movement. I'll post em here, as my guess is this ship has sailed for me.

I suspect they have two Speedmasters and got the images mixed up, if you dont know about vintage Speedies then I suppose its easy to make that mistake.

You need a time-out.