OK, I can't find the actual belt number right now, but here'* the secret:
Whatever the part number is, say 4060940 for example, the last three digits will tell you the length in inches. The number above would be a 94.0" belt to get a 94.5" belt, you would get a 4060945, for a 95" belt, 4060950, etc...
So go into your parts store, find out what size is standard, then ask what the next size smaller is. Sometimes there is a 1/2" smaller size and sometimes only a full inch difference is available. Let us know what you find.
Just don't go too tight. You will want some tensioning occuring and an overtight belt could damage pulleys.
Mike: 1997 SE w/ 183K, aka White Horse
, Gutted Airbox w/K&N, drilled 180* t-stat, tint all around, clear corners w/SilverStars, "PONTIAC" light up tail, PEMs, NGK TR55s