Tell me about my Speedmaster? Please?

Hi everyone

I'm new to the forums and this is my first post. #wave

I was hoping some of you may be able to help me out and tell me a bit about the Speedmaster Professional i just purchased a week ago.

Needless to say, I absolutely LOVE this watch and am just wanting someone to shed light on the possible year of manufacture and a proper reference number.

The thing that is confusing me is the serial number on the case (and movement).
It seems to be a late serial number, but the watch came with the pin and collar bracelet (which i also love).

Serial: 87317546 (also on movement pictured)
Case-back (pictured): 145.002, 345.002

Is it a 3570.50 (as the bracelet may indicate) or is it a newer reference (the current one).

I purchased it no box or papers, but from a very trusted source here in Sydney.

Any light you can shed would be greatly appreciated.

The first number is usually the standard reference number, the second is like a specialty number. it looks like a cal 1861

Thanks for the info so far...

heres the case-back...

No "Professional" or "Professional Moonwatch" on the case-back

Mine was purchased In 2017 from an ad with a serial in the 78 mil. Very confusing serial numbers these speedies come with.

My reference 31130423001005 was purchased in November 2018 and it has a 78 serial nunber, pushing toward 79.
I suspect it may also have been slightly older stock.

Going by the serial numbers, my Speedy Pro was built not all that long before yours with a 7878xxxx serial. Relatively speaking.