I plan to buy a new Silverado w/6.0 L when they offer it with the 6L80E in something other than a HD2500. Has anyone installed an aftermarket camshaft on one of the 6.0 L engines that has VVT without AFM? I'm wondering about the PHASER that mounts on the cam sprocket. All I've seen are photos, but it looks like some kind of spring loaded clutch setup. Is the centerline of the cam threaded to accept a bolt that holds the phaser on or does it use the existing bolts that hold the cam sprocket onto the cam itself?