It appears to be a 810.3 with an N ("Reverse Panda")dial, with a red seconds hand, perhaps a "long playing"? One site perhaps identified this as a 1969 "Jim Clark" model, but I also found that a Jim Clark was an 810.2.
The back is odd, as it appears the original model number has been obliterated and it's marked with a 810 and what I believe to be serial number of 1277305. I have not opened the back to confirm serial number or learn more, as I'm not sure I could get the back snapped on without doing damage to the watch or crystal.
Serial number 1277305 puts production at 1969, but I note that receipt shows it was purchased in 1973 for $87 (about $630 in 2025 dollars).
Anyway, just thought I'd share this info and some photos. Anyone have any ideas about that odd back?
https://ibb.co/VpzRVHRNhttps://ibb.co/xS4VBtnDhttps://ibb.co/ch9YwnLChttps://ibb.co/XfXyCJC0