Here are a few non-invasive (suction cup) mounts:
http://www.racerpartswholesale.com/speedprod15b.htm
Are you looking for a multi-camera setup that records stuff in your truck, or just something for occasional track runs?
If it's the former, you should look at some lipstick cameras. The good ones aren't cheap, but they take great shots and will last much longer. Toshiba makes nice ones.
If you just want to mount a camcorder for drag track runs, then go with the suction cup mounts.
I built a camera mount called the ShredCam. We use it to record video of guitarists playing. It mounts via an Irwin QuickClamp onto the headstock of the guitar and looks straight down the neck. The head/mount is custom machined by me, and the gimble is from a little webcam tripod.

It works quite well in the truck too. In my driving video, I have it clamped onto the back edge of the rear window. The window is only open about 1", and a foam insert used to fill in the gap. Works great, but could use a little more stabilization (softer rubber 'grips'). Pics available upon request.
Remember: Bungee cords are your friend!
And do a safety strap for the camera. It's bad enough that it might fall off, but if it damages the vehicle behind you, that would suck.