Prowler V6

[G. Scott Ponton]

There are four "standards" for fasteners. They relate to the thread pitch
more than anything although there are several different "head" sizes. Mostly
the Japanese/asian use 10, 12, 14, 17, 21, & 32. The europeon use 10, 13,
14, 17, 19, 21 and various larger sizes. Other than the English. They used
to use what was called a Whitworth standard. These are the 3/8 bolts with
the "15mm" heads. Actually they are 19/32. They also used 23/32 (i think it
was.) I haven't seen those wrenches since my tools were stolen. You used to
get them in every Craftman set up until about 1975.  You will also notice
that most, nearly all, of the English bolts are a "fine" thread pitch. It
isn't quite the same as SAE fine as the radius of the thread root is
different and although you can use one on the other they ussually are a very
tight fit and sometimes destroy the fasteners. Then of course you have SAE
standard inch sizes and the famous SAE standard metric sizes. Other than the
15mm the 16 and 18 are so close to SAE 5/8 and 11/16 that many times you can
use these sizes to remove them. Maybe had something to do with it at the
start.

Just my .02$

Scott