In my search for a hesalite/sapphire sandwich Speedmaster, I keep on coming across these strange, transitional models... Just now I have found this watch which apparently is a 3572.50 reference with what looks like a gilted 863 caliber inside. The warranty card is from Japan and is dated 1997. Now, I'm well aware there was a short window of time when they used tritium markers in 3572.50, but I haven't yet heard about 3572.50 with the old 863 movement... That said, I'm a complete newbie so perhaps someone can correct me if I'm wrong! Or, could it be that the watch had the original movement replaced? I'm posting a couple pictures of the watch in case it helps. Many thanks!