5512 4th Gen

[patony]

I stumbled upon this guy at a rural auction. I really only know the basics about Rolex and have generally focused on off-brand vtg chronographs but I couldn't pass this one up.

Marked 5512 with a serial in the 1.2M. The bracelet is 7206/80

The watch (signed on the case back) belonged, only found this out after googling him, to a pilot and scuba instructor.

The crystal is scratched..how detrimental to pricing is it for me to replace this?

Any other thoughts on the specs for this one that would be considered minute, but important details? I don't really understand the difference in Mark I/II dials, matte dial, etc...

Has it been redialed? Polished? Things that look like they've been altered?

Any thoughts would be immensely helpful!