As standard, a 1999 car will have had a studded windscreen and no header rail on the hood. AW grind the studs off and re-fit the windscreen with what was the studded face inwards. When they did our old car (13 years ago) the face of the windscreen was made good with a substantial black tape.
The notch and peg arrangement you describe sounds very like the Allon White conversion. I am fairly certain that AW had a 4 seater conversion at one time. The refined their offer more recently when they stopped offering to convert an existing hood fabric and only offered a new hood as part of the conversion, Worth a phone call if they have people working - I suspect they will have a record of your car if they did a conversion on it.
Good luck in your quest for a solution.
Last edited by Paul F; 06/05/20 09:04 PM.