I didn't read all the posts but yes, you can do this yourself if you have any mechanical knowledge. It's not difficult, it's just a little tedious. There are a few YouTube videos showing how to do it. I think the only difference between the gas motors and the 3.0 is that you have to drop the exhaust on the gas motors, NOT the 3.0.
In addition to the filter and pan gasket you will need new bolts for the filter as well. You cannot buy just those bolts though. They come in a service pack for something else within the transmission but you won't need those.
I did mine a few months ago at 20K just to get the original fluid out.
If anybody wants me to, I can do a quick write-up and try to find the videos of the procedure. You will need a fluid pump to put the fluid back in the fill plug on the side of the transmission. You could spend a few hundred on a Motive one but I made one for about $20 using a Home Depot sprayer.
Just let me know.