Rick the repops come with or without the rib (fin). I still have my original 68 and selected the same one as it had with the rib.. Regardless pretty much useless IMO due to the small size. 69's are slightly bigger. The after market passenger side is totally useless and there mostly to just keep me from hitting the garage door backing out.I have 69 style repops on my 68 and they don't have the Fin line down the back edge and all the repops I've looked at didn't either but it's possible the mirrors you have came from another model GM ??
Great info! Thank you. I know the mirrors on my last 69 didn't have the parting lines on either driver or passenger side mirrors, and those were original mirrors on it. It was a Baltimore built car. When I seen the parting line on my current Chevelle (Fremont built car) it made me question if the mirror was original or reproduction, because I've never seen one with that line before, but from everything I've researched over the last few days, it appears to be original.That is a casting mold parting line. How much of it would remain on a finished new mirror depended entirely on how aggressive the worker was in smoothing it up before sending the part to plating.
On original 66-67 mirrors (which have the same base as the 68 and 69 mirrors), some have the parting line and some don't. Donnelly Mfg. (that's what the DMI on the glass means) made the mirror glass and assembled the mirrors, as well as at least two other suppliers. But I believe that the bases were cast and supplied by sub-suppliers (and at least 2 or 3 different ones), because there are different casting numbers and other mold-maker marks on some originals than on others, and some of them have the parting line and some don't.
I have always heard the 69-70 concours resto folks say that a 69-70 mirror MUST have the parting line to be original, but I am not so sure that is true, given that the same suppliers were involved as with 66-67 mirrors, and the base is the same part ...