The mirror code which shows up on the fender tag can be described different ways. Single or double mirror codes that show up on the broadcast sheet typically say MIRROR O/S LT or MIRROR O/S RT. This gets more complicated as the codes and broadcast sheet format changed for different model years. I was able to find some window sticker/fender tag/broadcast sheet examples showing some of this. 1974 adds more G codes.
SINGLE RACING MIRROR
You can have a single driver side chrome (G33 in 1970-1971, G35 in 1972-1973) or a painted (G34) mirror and not have a matching passenger side mirror. The fender tag for the body assembly guys, the window sticker for the pricing, and the broadcast sheet for assembly line parts availability would all have one mirror code in this case, either G33, G34, or G35. 1974 had yet another mirror code change which ended up as poster
volunteer said above, G54 for painted Outside Left, G64 for painted Outside Right, and G74 for Outside Left/Right. A 1974 broadcast sheet example is shown later in this post.
Here is a 1972 fender tag which would be G35 -
Mirror O/S Left on the broadcast sheet and a different 1972 Challenger's window sticker showing G35 - RACING MIRROR-LEFT REMOTE-CHROME for $14.95. *Note this is for one Single Chrome Racing mirror on the Driver's side which would replace the standard G31 Chrome mirror.
DUAL RACING MIRRORS
If you have a fender tag code of G37 for DUAL CHROME RACING MIRRORS, your 1973 window sticker would also have G37 for Dual Chrome Racing Mirrors and you would have G37 on the broadcast sheet. Same would apply for a G36 painted mirror code.
G37 line enlarged from the 1973 window sticker below.
And here is a 1973 Challenger fender tag with G37.
And also a 1974 broadcast sheet showing the G54 - MIRROR O/S LT, G64 - MIRROR O/S RT, and G74 MIRROR O/S LT/RT mirror codes. Why three codes when just G74 would have worked is anybody's guess?
Hope this shows some of what the mirror codes were for different years. I will edit the previous table to add what I found.
Bottom line is I believe the answer to bandit 73's earlier question on his G35 mirror code is his car came with the
G35 - RACING MIRROR-LEFT REMOTE-CHROME.