CA

CA is pretty brittle, not flexible.  I would try putting the model in the freezer for a bit then light, sharp taps on the shell to break it loose.  Hopefully, they did not prepare the surfaces well and the paint in the joint will give way before something breaks.  

Acetone will dissolve the CA but will also dissolve the shell just as well.

Good luck,

Paul

Try a broad blade too

depending on where and how it was glued after visiting the freezer, try working the body away from the frame with a broad flat blade, spatula or even steel rule (I know not a tool -but if that's all he's got then) and hopefully the glue will break being careful not the damage the shell.

if you do have to Drexel, study the join carefully and make multiple passes on the the line of attack to minimize any damage caused by the cutting. Once apart you can then look at rebuilding the cutoff part by (ironically) CAing styrene back onto frame to rep,ace the removed peices.

Good luck 

Simon

"Somewhere along the line,

        CA is not great for metal to plastic joints so depending on how much CA they used you might be able to just pop the joint apart with a thin screw driver or other blade....DaveB 

Finally,

 After about a year of trying to get the shell seperated from the frame, and an over night stay in the freezer, I found out that who ever had it before me really went to town with the CA. It arrived that way, it was an ebay purchase.

  The entire length from the rear of the cab to the back of the front steps had enough CA on it to do several projects.  Out over the front porch the paint seperated from the frame, (that's no big deal) even though it was in the freezer overnight, it was still a bear to get them seperated. Three different screwdrivers & a 16 oz. hammer were what it took to get the job done.

Thank you Gentlemen. I greatly appreciate you assistance.

Charlie