Help with authenticity for 3572.50

Hi,

I am hoping to buy a omega speedmaster 3572.50 to start my collection
I have found a watch online that I am very interested in (photos attached)

However, I noticed on the display back that the movement has a gold wheel on the top right. I know the sapphire sandwich models have a gold wheel in that position but almost all the 3572.50 I have seen have a rhodium grey wheel in that position. (photo for comparison also attached)

Is it possible for a 3572.50 to have a gold wheel in that position or has it been altered?
If it has been altered does that diminish its value or imply it may be a fake?

Other general comments about the watch also very much appreciated

Thank you!

Thank you very much for your help!

Did you end up getting this? I am on the search for a 3572.50 with a 863 and Tritium Dial.

I think all 3572.50 comes w/ 1863 movement.