Real or Fake?

[Waiwaib]

Bought my first pre-owned Rolex in mint condition this weekend and would love to have the forum weigh in on their thoughts regarding its "authenticity" from far away

16233 DJ (circa 1989/90?) - 6 and 12 o'clock was exposed on the band to show inscriptions of model and serial number
L Series
Clasp shows N- 12
Black MOP (Aftermarket)
Opened the casing to display the 3135 movement
Box and manuals in pristine condition but no cert (not looking to resell but does give me an uneasy feeling)

Not sure what else I missed in reviewing my purchase. Would appreciate the experts opinions when I go in search for my second