The early 1970 Gt V6 were fitted with the small bullet type mirror where as the later were fitted with the tear drop type (XA type).
I am not 100% sure of the exact date of the change over (mid 1971 I think) but it would have to be after 4/1970 as mine is fitted with the bullet type mirror.
So assuming only fitted to the early cars (also like the fake rear cast vent in the bonnet)  and early non GT's fitted with chrome mirrors makes that type of mirror harder to find and maybe thus the bidding chaos for the one listed.
 
 
Here is a link to a earlier discussion regarding capri side mirrors.
http://www.classic-ford.org/cfp/tm.aspx?m=60429
 

they did come out on some v6's - heres the lowest km (1637), most original one in aust - with one
 

From the photos it must have been a very hard 1,637 kms!

I would whip that off and stick it on ebay before the other bidder loses interest!

No the k's weren't hard, sitting under pine trees for 20 years was. yes the mirrors worth more than the car! Ill use it one day when i fix the car up - one day .... Like wools - i wouldnt pay $1600 for one though - originality is nice but ..

1637 km's - wow... whats the interior like on it ? Black / tan ?
 
Paul

tan - all intact - nothings ever been removed - so has all of the little trims etc, orig radio, parcel tray etc - loom is like new

Well well well, didn't take long did it
 
 
http://www.ebay.com.au/itm/GT-mirror-x-1-genuine-Ford-suit-Capri-Escort-Cortina-Lotus-Twin-cam-L-R-mirror-/321578824471?pt=AU_Car_Parts_Accessories&hash=item4adf977317

Its definitely off a 1970 mk1, the brochures on the previous page were for a 1971 V6 and 1969 GT, the 1970 V6 definitely had this mirror as I had an 04/1970 V6 as well as having the brochures still.
 
He must have a few parts for a 1970 as he also sold the dummy vent at the back of a 1970 V6 bonnet for $152.50 which is really good price as I was paying $30 each for them in 1980's as I was trying to open them up without cracking to allow some real air to get in.......

I just found a pic of one on a 4/71 V6.