I am the fourth owner of a 1991 318is. It appears the car suffered an impact at the right front corner. I thought the front bumper was uneven, but it's actually a small divot in the body. Also, there are parts missing from the right side that are present on the left side. I'm having problems tracking one of them down...
On the left side, I have a black plastic headlight cover. (See attached pic.) It is one piece but has two part numbers: 51711965245 and 51711965243. I ran a cross-reference for both part numbers on realoem.com. RealOEM.com Part Cross-reference
and RealOEM.com Part Cross-reference
So, according to RealOEM.com, my car has neither a left nor right headlight cover.
If you have a 1991 318is, I would appreciate it if you could let me know whether your car has a left and right headlight cover and what the part number is for the right-hand one. Thanks.