SU size determination

[Doug Mathews <tr3run@peachnet.campus.mci.net>]

I belive the older su's were 1.50 and the later ones were 1.75. Is there a
surefire way to tell which a carb is? I've some "extra" ones that I'd like
to see what size they are and make sure I have the larger ones on a 64TR4.

Also, I have the original Zenith's that were on the car. Whats folks
opinions on which ones to use? SU or Zenith?