So I was curious about the Vortec Max trucks and did some googling. Apparently there were different packages. So here's what I learned:
The gmt 800 trucks with the Vortec Max option got the LQ9 (essentially, possibly the very same thing... I didn't research), a 4L70 trans and the 14 bolt axle, although with drum brakes. Beyond that, there was the 4x4 version that had a trailering package with ride control, 17 inch wheels, a gov-loc and 4:10 gears. That's the one I remember in the magazine ad. It also could not be combined with the Z71 option. But there was also a 2wd version with a performance suspension and 20 inch wheels. From what I gather, it was basically a poor man's Silverado SS.
For the gmt900 trucks, the Vortec Max emblems on the doors just meant it had the LQ9 under the hood. The trailering package with the 14 bolt was a separate option. It also could be combined with the Z71 option.