I'm passing along this info in case it's helpful for anyone. The original NAS 90 rear view mirror is a Donnelly model 2410 as discussed here. It is no longer in production. I searched on eBay to find one and most of them are for a Ford and they have the incorrect mount. The Defender version has a set screw. I found the exact mirror was sold by CIPA as part # 32000. They still sell that mirror new, but it is no longer the original Donnelly 2410. They switched it to the Donnelly model 240 and then to a low quality reproduction of the 2410. So if you want the original search for an old stock CIPA # 32000.
There are photos of the original mirror here: Espejo Retrovisor Land Rover Defender Mxc3340 - $ 6.890
I rolled the dice and bought three old stock CIPA mirrors on eBay. One of them is the original Donnelly 2410. One of them is the Donnelly 240, which is the same size as the 2410, except it has rounded corners. The Donnelly mirrors are 9 1/2" wide and made in USA. The third one is a Chinese reproduction of the 2410. It's low quality and slightly larger at 9 7/8" wide. It is probably the one that is currently sold new, although I believe they sell a reproduction of the 240 as well and it may be random which one they put in boxes.
Here are the three different CIPA #32000 mirrors.
This is the correct Donnelly 2410.
This is the original 2410 compared with the reproduction.
This is the original 2410 compared with the original 240. They are both 9 1/2" wide, except the 240 is oblong shape rather than rectangular. The mount is also wider for the 240 so they are not interchangeable without replacing the mount on the windshield. It comes with a T20 Torx screw instead of a Phillips. The Torx screw is shorter and cannot be used on the 2410. The 240 is a very nice mirror, and while it is incorrect for the NAS 90 in terms of originality, it is close to the shape of the standard RoW Defender mirror.
This is the 2410 compared with the original mirror from a 91 Range Rover. It's identical except for the markings on the back and slightly different shaped day/night switch. My best guess is that it's also a Donnelly mirror. So I'll call it an "early 2410". That mirror was sold by Yankee in the aftermarket.
There are photos of the original mirror here: Espejo Retrovisor Land Rover Defender Mxc3340 - $ 6.890
I rolled the dice and bought three old stock CIPA mirrors on eBay. One of them is the original Donnelly 2410. One of them is the Donnelly 240, which is the same size as the 2410, except it has rounded corners. The Donnelly mirrors are 9 1/2" wide and made in USA. The third one is a Chinese reproduction of the 2410. It's low quality and slightly larger at 9 7/8" wide. It is probably the one that is currently sold new, although I believe they sell a reproduction of the 240 as well and it may be random which one they put in boxes.
Here are the three different CIPA #32000 mirrors.
This is the correct Donnelly 2410.
This is the original 2410 compared with the reproduction.
This is the original 2410 compared with the original 240. They are both 9 1/2" wide, except the 240 is oblong shape rather than rectangular. The mount is also wider for the 240 so they are not interchangeable without replacing the mount on the windshield. It comes with a T20 Torx screw instead of a Phillips. The Torx screw is shorter and cannot be used on the 2410. The 240 is a very nice mirror, and while it is incorrect for the NAS 90 in terms of originality, it is close to the shape of the standard RoW Defender mirror.
This is the 2410 compared with the original mirror from a 91 Range Rover. It's identical except for the markings on the back and slightly different shaped day/night switch. My best guess is that it's also a Donnelly mirror. So I'll call it an "early 2410". That mirror was sold by Yankee in the aftermarket.