help me out -choosing midsize president vintage

[iheartvintage]

hi im really in a market for a preowned vintage late1980 early 1990ish midsize president with champagne dial

i saw a few on ebay, can someone please advise their legitimacy? i really dont understand anything about watches, can they replace the original parts/change it mess with it..any help will be appreciated

here is the link:

http://cgi.ebay.com/Rolex-18K-YG-Mid...item563f014660

http://cgi.ebay.com/Rolex-Watch-Mids...item35a7f64bff

thx so much