I would stick to ACdelco plugs the 3.5 depending on the year require AC 41-101 with a gap of .060 inches for the 05-06 models, and 07 and newer require AC 41-100 gapped to .040 inches. As far as how to, make sure your engine is cold and you use a spark plug socket with a ratchet to unscrew them and screw new ones in, be careful when pulling the boots off the spark plugs, do not pull on wire, pull from the top off the boot. To get to the back ones it is easier if you remove the alternator. I replaced my wires when I did my plugs, but if you are flat broke you may want to wait. I used Magnecor 8.5mm wires instead of the OE AC Delco, the Magnecor are better and about the same price.