Sounds to me that youare looking for a 'Carvair'. This was (I was told long ago) a modified DC-6. It was, and still is, usaed for hauling cars.
Until last year, there were 2 based in Griffin, GA. One crashed while attempting a 3-engine take-off. The other is currently based at Tara Field, adjacent to the NASCAR track just south of ATL.
I think there are photos available under the 'props' section here at airliners.net. I'll look and get the photo #'s back to you.