Here are some pics of my 68 panel's rear view mirror. If you have the original wooden partition wall between the cab and the cargo area, the longer stem is a must to see anything.
There are many mirrors for sale here in the bay window bus classifieds
http://www.thesamba.com/vw/classifieds/search.php?submit=yes&type=text§ion%5B%5D=33&keywords=mirror" onclick="window.open(this.href);return false;
Including this NOS one in the Netherlands. Ouch! And the next one is even more expensive!!!
http://www.thesamba.com/vw/classifieds/detail.php?id=1207906" onclick="window.open(this.href);return false;
The last one in the first link is in very nice condition! From the Netherlands.
http://www.thesamba.com/vw/classifieds/detail.php?id=1364210" onclick="window.open(this.href);return false;
Or maybe the split window classifieds?
http://www.thesamba.com/vw/classifieds/search.php?type=text&stype=all&keywords=mirror§ion%5B%5D=31&sort=date&sort_order=DESC&page=0" onclick="window.open(this.href);return false;