linear IC suffixes

[JBaker]

Several of the circuits I'm looking at call for linear IC's, however the
parts list usually only calls for a 'TL071', 'TL082', 'TL084', etc.,
with no suffix.  Consulting my Mouser catalog, I find that there are at
least three different types of each of these (not counting the surface
mount types) with suffixes like 'ACN', 'CN', and 'IN'.  What do these
suffixes mean?  I would readily spend $1.10 for an 'ACN' type if I
thought it performed better than a .60 'CN' type.

Also, now that I have looked in a few different places, I'm beggining to
think that the  'LM1448' is hard to find.  Anyone know offhand where to
get one, or is there a good substitution for this?

thanks,
Jeff