Unfortunately, except for Starrett, who made theirs fairly similar 
(uniform) over time,
there are about 137 other sizes and styles.
  The marking pins and the brass bushings that go into the head as well.

Long short fat thin, and their little bushings too.

I have a little sack of maybe a dozen spare marking awls.

Last time I needed one for a square I was cleaning up?
  I had to custom fit one anyway. :-\
     yours Scott

-- 
*******************************
    Scott Grandstaff
    Box 409 Happy Camp, Ca  96039
    scottg@s...
    http://www.snowcrest.net/kitty/sgrandstaff/
    http://www.snowcrest.net/kitty/hpages/index.html