If you mean that the belt is too short, I had the same problem. It appears that the belt specified in many of the parts catalogs is wrong or they use the same belt for several different configurations. I finally had to try a bunch of different ones in the parking lot of my friendly Autozone. I have a 94 Jimmy with a 4.3L and it uses a K060938 belt. This means that there are 6 ribs and its 93.8" long.
Rockauto.com shows belts of K060938, 940, 955, and 956 for the 94. For your 97 they show belts from K060870, 875, and 960. You might want to check Rockauto out they have a pretty good selection and it's easy to navigate.
Now if your just having trouble getting the belt over all the pullies, welcome to the club. I have found that if I seat the belt on all of the pullies I can slip the remaining loop of belt over the tensioner with just a little to spare. Watch that you don't get your fingers between the belt and the tensioner,if the wrench slips it'll squash your pinkie. It's inportant that you get the belt seated on the pullies , the extra you use up will make the belt seem too short.
Good luck
94