I noticed today when checking out that area of Harlem that her fuel cap has a small plastic “strap” on it that attaches to the cap on one end. The other end is apparently supposed to attach to something else nearby … presumably to keep the cap from getting separated/“lost” from the car. 
I have looked all in that area but don’t see anything that the tiny “snap cup” on the end of the strap could attach to. I see in the owner’s manual that it appears to attach to something on the bottom of the fuel door, but, again, I don’t see what. 
Ah, looks like the attachment point is a small hole adjacent to the base of the flap’s rubber bumper. I’ll look for that now … (btw, that Ebay vendor is my go-to guy … located just like 30 miles east of me. His place has over 2,000 used XJ8/XK8 parts! 
) Thanks! 