Not knowing what year your truck is I did find this post by mdoyle and how he replaced his switch in his truck, 2003 model year I think. The part number is different but that could be the difference from 3/2007 and now.
http://www.elcovaforums.com/forums/s...ad.php?t=25841
Edit: It has also been said to have a locksmith replace the switch versus the dealership.
"Today I finally decided to fix it and thought I'd share the info. The part you need is an "ignition and start switch" part number 15242754 and runs $38.50. You'll also want to ask for a copy of documents:
834551 Steering Wheel Theft Deterrent Lock Replacement
847831 SIR Disabling and Enabling (to prevent air bag deployment)
841952 Ignition and Start Switch Replacement
Start by pulling the negative battery cable to disable the air bag and then remove the bottom steering column cover, it just pulls off it's locking tabs.
The upper cover is retained by one male torx fastener. You can use a 5/16" six sided socket if you don't have the right adaptor. Then the upper cover separates from the column.
Then use a small flat blade screwdriver to press the release on the theft deterrent lock harness connector, then press the plastic latch to easily remove this part. The document shows prying it, but pressing the latch is easier. The same goes for the key alarm connector, there is a tiny release tab you can engage with a small flat screwdriver so it's removal is easy.
The rest of the procedure involves unplugging two more harness connectors and finally the ignition/start switch can be unslid from the housing. One thing not covered in the manual is the position of the key relative the switch housing gear. Make sure you position the new switch in the same position as the old one.
After you install the switch connect everything up and test it before putting the housing back on. If the key sequence is off, release the ignition/start switch and reposition the plastic gear manually.
I did a post-mordem on my old switch and it looks like they are using slightly different components than 2003. I think the problem with mine was wear on the white switch gear that didn't totally take the ignition out of circuit when the key was removed.
It seems to have solved the problem, I won't know for sure until a couple of weeks of driving have gone by since it was an intermittant problem. The whole repair took about 30 minutes. Hopefully this info is useful to others."