It is a 66 Chevy c10 fleetside, however between the cab and bed the frame has weld marks that appear to have modified. I may have a cab from 66 and a bed from a 64. Not sure.

Here are some more pics

http://i387.photobucket.com/albums/oo320/msgdesign/1966%20Chevy%20Pickup/pic-2.jpg
http://i387.photobucket.com/albums/oo320/msgdesign/1966%20Chevy%20Pickup/DSC_0023.jpg