Need Help Authenticating a Rolex Day-Date 1803

[drtruck]

TL;DR: Need help authenticating this Rolex Day-Date 1803. Seems mostly legit but have some concerns about the bracelet.

Images are attached in the zip file since attaching photos would not work for me.

Hey all, my grandpa showed me this day-date 1803. It was an engagement present and he's only ever worn it once. It came in a red box, has a linen dial, I managed to set the day/time and the movement still felt brand new. Was a little confused by the bracelet clasp though since I've never seen it before.

If anyone can help me authenticate this watch I'd greatly appreciate it!