I need to get new side mirror replacement glass for my 1971 Road runner.
Where can I source them?

Anyone that cuts glass can make you one.

https://burcoinc.com/redi-cuts-catalog/

search by application, but you'll find 2101 is roud mirrror and 2122 is the racing mirror.

Several sellers for these into $18-22 rate...except bradsnosparts in $50 LOL

Editing:

sometimes even the PAIR for that rate LOL

https://www.ebay.com/sch/i.html?_fr...c=0&_odkw=red+cut+2122&_osacat=0

https://www.ebay.com/sch/i.html?_fr...esc=0&_osacat=0&_odkw=burco+2122

Thanks Nacho for the info.
Looking on the Burco website I see they have mirrors for alot of the later model vehicles.
So my question is - what later model application side mirror would be close enough for 1971 B-body?

I used a 2101 for my 68 Dart. The dimensions are very close, but a hair smaller than stock. Small enough that you would see a silver ring around the glass from the backing plate shining through. I used some flat black spray paint on the backing plate edges before installing mirror so you did not see.

Thanks for the info guys.

I'll second that. When I needed to replace one quick for my truck I went to a local automotive glass shop I always use and they cut the mirror and replaced it while I waited. Cheap and quick. I tried buying a replacement online once and it didn't fit and was around the same price anyway.

I don't get why you would need a "close enough" side mirror from a later application if the right one is available?

On a side note, is true you can go to a glass shop and get one cut to fit, but if you want to buy, that's one of the options available!

Looooong time ago Rockauto had them available from several manufacturers. I got one at Rockauto, althought is still packaged, haven't replaced the glass yet. It's there to replace the glass when rechroming the mirror housing because I can't get loosen the screws attaching the glass base/pivot assembly to the housing with glass in place ( screws are stuck ), so will need to break the glass sooner or later to reach them straight with a screw driver and not angled from a side.

I could not find any local glass shop, home or auto, that would cut round glass. And these were locations that made custom mirrors for homes. You would think I was asking for something super complex, it is just a circle.