What length Serpentine Belt?

I'm looking to replace a cracked serpentine belt, but I'm told there are two different designs: 1st Design, 2nd Design, with 2nd Design being millimeters longer.

I'm using a 1997 GPGT, 3.8L, non-supercharged. I was told that there's a code on the alternator, either n4 or b3, to determine my belt size, but I can't find it. Any other way of finding out my belt length, short of taking it off and sizing it up?

The second design is approximately 1/2 inch longer.You'll probably have to remove it and size it up. Also, check for any brand and manufacturer part number on the belt.