Now that is an UNUSUAL truck, and a sharp eye FriedGreenTmater! That is definitely truck number three spotted thus far with option #389 (plus some serious fabrication). Looks like the shortened bed and extended cab required the fuel filler tube to emerge between the cab and bed rather than bedside, creating a wider than normal gap betwen the two?
Don/RdsLessTaken

'47 Chevy with option #389 running boards
[IMG]http://i1291.photobucket.com/albums/b542/RdLessTaken/RdLessTaken%20Trucks/IMG_20335_zps508f9951.jpg[/IMG]