There should be 2, a left and a right. ones a low tone and the other is a high tone. If your horn sounds funny then one is out and you'll need to know which one it is.. They are located behind the grill mounted to the radiator support around the headlight area on each side, you may have to pull the air box or battery to get to them. That's where mine were on my 2002 and I don't think they would be to far away from that location and all years take the same part number as do most gm cars and trucks for 50 plus years.. Believe it or not..
High Note Horn - GM 84594588
Low Note Horn - GM 84594590
Although I believe they finally changed them in last few years..