timing belt?

What kind of timing belt/chain is on a 97 Bravada. I just had a major problem with a timing belt breaking on my 94 Grand Prix and really messing up the engine. I was told the timing belt should be changed at regular mileage intervals. I love my truck and don't want to see the same thing happen to it that just happened to my Grand Prix. I don't think I can save the Pontiac. (Broken camshaft and timing belt) My truck has 149,000 on it, and I don't know if the timing belt has ever been changed. Is this bad? Should I have it changed? What is everyones thoughts on this?

Your Bravada has a steel timing chain. You're right to start worrying about it now. I checked mine at 177K on my '92 and it still looked pretty good but I replaced it anyway.
When you change it, put on a new water pump too while the front of the motor is apart.