Parma makes a number of bodies that fit short course truck chassis. Rally car, 57 Chevy.... none come painted tho. If pre-painted is a must, you'll have to pick from "factory replacement bodies", which will limit your choice of body style. But what you're looking for is something that will fit a short course truck chassis.

Painting isn't that hard. If you can use a spray can, you can paint an RC body. Look it up on YouTube. All you need to do is wash the INSIDE of the body with soap and water carefully getting into all the corners. Apply the window masks, then use a Scotch Brite pad to scuff the inside, again, paying attention to the tight spots. Give it another wash, then let dry. A one color paint job is as easy as pie. Just mist the inside of the body with a light coat and let dry. Do that several times until you get full coverage. Then back up your color coat with a black or silver backing coat to protect the color coat. Done!

Want racing stripes? Use masking tape where you want stripes, then paint the main body color until you get full coverage. Remove the masking tape then spray the stripe color. Then spray the backing coat. Viola! Two color paint job. Not hard. Give it a shot.