For whatever reason it's mainly Chevy stuff on there. Only Olds stuff is on the Cutlass 442 from '69-'72. Sorry man. However they do have Cadillac stuff from the early 1900s which is just plain fun to sift through.
You're right. The 4.2 doesn't seem to be included in the 2006 manual. The 2007 doesn't neither. The 2008 does and should work for you as I don't think there were many changes between 2006 and 2008, if at all. There were some changes between 2004 and 2006, such as the ignition coil design and a different crankshaft position reluctor ring (increased number of teeth) and the PCM was changed. Biggest change between 2006 and 2008 is that the electro-viscous fan clutch was dropped in 2008, going to a regular thermal only clutch.
I have an '08 Envoy Denali, and am looking for the service manual. I clicked on the link on the first page for '08 TB service manauls' figuring the only difference is sheet metal. However, what I got was the owners manual. Am I doing something wrong?
When you open that zip file, there is a folder inside marked 2008. Open that one and there is another folder inside of it also called 2008 along with the two PDF of the owners manual. Open that 2008 folder and all the manuals are in there.