This may be a duplicate message due to my inept command of e-mail.  Here goes a
gain:
 
There are several directories that contain lists of production services compani
es.  The directory that happens to be close to hand is PRODUCER'S MASTERGUIDE,
edited by Shmuel Bension (that's the correct spelling of his name).  I have the
 1988 edition, there may be later ones, I know there were earlier editions.  Th
is particular directory is worth looking at since it includes a wide range of i
nformation about production such as union and guild contract terms, lists of fi
lm commissions, list of various types of production houses, and a useful summar
y of the business of feature film production.