Valve noise and Hayes Repair Manual

I am getting a lot of noise in my lifters, rocker arms or under the valve cover of my 1998 Chevy Cheyenne CK 305 V-8 VIN 1 GCFC24M4WZ254020. The Hayes manual says "On 1991and later 7.4L V8's there are no provisions for valve adjustment " It goes on to say that there is a positive stop shoulder for the rocker arm. Yet later in the manual it says you can adjust the number two, five and seven intake valves and the the number three, four and eight exhaust valves by turning the crankshaft one complete revolution or 360 degrees and adjust the number three, four, six, and eight intake valves and the two, five and six and seven exhaust valves. It says to refer to section 3 install the covers and listen for noise in the valve train, check for oil leaks.

So it this what I have oil leaks? I hate Hayes is there a better manual I can get with real instructions. Or can you provide my answer? Thank you for your time.