1995 Chevrolet Silverado Drive belt tension

You use a tool to pull the spring-loaded arm to release the tension from the belt. There will either be a square hole in the arm to insert a ratchet or breaker bar, or you use a box-end wrench on the hex nut in the middle of the pulley.

First, thank you for responding. WHERE can I find the "spring-loaded arm" you refer to in your answer? Where do I find the pulley (there are several, as you know). The hex nut on the middle pulley won't budge with a ratchet. What tool do I use to pull the spring-loaded arm to release tension from the belt?

The tensioner has a pulley that sits on an arm and is not bolted right to the engine. Yours should be a black pulley sitting next to a silver round housing. That's what has the spring in it. You would use a wrench on the bolt head in the middle of the black pulley to turn it to remove the belt tension. If you still can't identify which one it is, tug on the belt fairly hard and you should see the pulley move. It usually takes a 15mm wrench to turn the pulley but GM has used 16mm bolts a lot too.