I know I'm resurrecting an old thread but I wanted to thank iheartgroceries for the walk through, knowing the bolt sizes saved me some time. I did not need to remove anything but I did unbolt and disconnect the intake piping to get to the rear drivers side plug. Just used a spark plug socket and extension. My plugs were in crazy tight so I had to use my torque wrench to remove them. Having done it now I bet I could do this again in about 30mins. The rear passenger side was accessible by just bending the wires a little. On a final note my SP534's were all gapped at .030 out of the box, even though everywhere on the net says .035.
Here is a pic of the first 2 plugs I removed next to a new plug for comparison. This is on my Explorer after about 36k, and a couple runs at the drag strip last year. I'm thinking we might have just a little more space to work with on the back plugs in the explorer than the guys with the sho. Oh I got the plugs and the little gap device from oreileys for $27 after tax. Can't believe I paid $100 for plugs from LMS and another $100 for install from the dealership last year (just wanted it done). Anyone debating doing this them selves, I say go for it, probably one of the simplest things to do on these vehicles