1999 gmc yukon no start

[c20pickup]

hey guys i went to start my yukon tonite and nothing happened, no click, didnt turn over no unusual noises all i had was a dead key. battery charge is good, lights went on no problem, turned the key and it was dead. i didnt even hear a click. this is the first time this has occurred. i pulled the starter relay, ignition fuses a&b, and a few other related fuses, all looked to be in good shape. when the key is turned i can hear a faint clicking coming from what seems to be the back of the engine. culd this be a starter issue? anything other suggestions where to start? this vehicle has 184,xxx miles, bone stock as stock can be and always maintained (vehicle has been in my family since new). 5.7 vortec engine by the way/