Remove Serphatine Belt on 2001 Chevrolet Silverado 3500

I can not find a way to release tention on belt there is no tension release which I can use a 3/8 drive on
it is a 8.1 litre no tension release just pully below alternator.
Ok found the tension release it had no rachet hole you have to use a 5/16 sock on top of tension pully to release tension thanks folks..

There is a 3/8 square hole on the Idler pulley to use to loosen the pulley to remove the belt.The pulley is spring loaded.Put a 3/8 drive 4" extension on a 3/8 drive socket wrench & insert it in the 3/8 hole.Just pull & the pulley will move to pull the belt off.You'll have to hold the pulley with the wrench untill you remove the belt.