Well you could clamp the top onto the greenie as temp storage and work space. Is the wind blowing in the 50s up there too today?
On the mirror nuts/threads.
There was a whole thread on the threads.
http://67-72chevytrucks.com/vboard/s...d.php?t=564182
But to the bottom line.
"Did some flipping through my catalogs and a lot more through the GM parts Wiki.
The original nut was P/N 331545
It was superseded by P/N 14016610 (3/8-20 LOW CROWN)
Unfortunately it is listed as discontinued.
But the thread is listed as 3/8-20 not the more typical 3/8-16 UNC or 3/8-24 UNF threads..."