https://www.ebay.de/itm/272712792900Purchases made through these links may earn this site a commission from the eBay Partner Network Dial and bezel obviously! But what kind of dial is that?
I do not think that that is a genuine Omega service bezel, and I do not know if that style of service dial was ever available for the 861... the whole presentation of this watch is fairly fishy too, odd angles and nothing coming anywhere near a head-on shot.
I have developed parallax-correcting software and I managed to turn one of those photos into a fairly decent head-on image. Looks legit to me.
I think maybe modern 321 service dial modified to fit an 861. Here's some pics from the Ebay listing Dial is Swiss Made, like the modern ones and looks like SL to me.