You are right, it is not one of those molded plastic, body integrated, lens covers. I have them on my '98 Dodge family van and when they became cloudy with age I was able to greatly improve them with a sanding and buffing kit I got at Kragen. The '91 Isuzu "headlamp" is described as a "composite headlamp" on the parts list, because the glass lens houses both the halogen bulb for the high/low beams and another bulb for the running light. Isuzu was making some headlamp changes for the '89 to '91 years and I gave the parts house the VIN number so they could be sure of the correct lens. By the way this site is a great listing of all Isuzu parts numbers. myisuzuparts.com