Small Claims Court allows you to sue (up to $7,500)for things like this. The following is from the state's website explaining things that can be brought through the small claims system
"You were defrauded in the purchase of a car, and desire to cancel the purchase and get back the amount of your down payment from the seller"
Here is the site:
http://www.dca.ca.gov/publications/s...sic_info.shtml
Disclaimer: I did not read the information posted so I don't know how it works for people from out of state.
In a nutshell, small claims is fairly easy (I went through it once). To win, the burden of proof is only the preponderance of the evidence. Basically if you tilt the scales of justice in your direction,51%, you have a winning case (as opposed to proving your case "beyond a reasonable doubt" in criminal cases).
I think if you could document or prove to the judge that you specifically asked about it being an original short bed, and can show that he assured you it was, you are starting to tilt the scale in your favor (he could have replied"I don't know" "How can I tell" "The guy a bought it from said it was" etc.).
If you go that route, document everything. Judges love evidence. Also consider having it appraised and then getting the appraiser to give a value for long bed vs. shortbed vs. modified longbed. That will give you a number to show your actual damages if you want to keep the truck but be made whole on the difference in value and what you paid (if there is a difference).
Lastly, as stated by someone above, the hard part can be getting your money after a judgement is passed. That involves another set of processes unless the person is a good person who just pays up.
Good luck. Nice looking truck even if cut down.
Frank