Whatcha got there is one of dem super rare 1953 flatfender CJ-7s on a Willy's truck frame. They only sold 7 of those, so it's one of the most rare vehicles ever made.
OK, Just kidding. I got no idea. I agree that the frame looks way too big for an old flatfender body. The curve and the length from the door to the fender in photo #2 make me think CJ-7 - when they stretched the cowl length.
Do those fenders look like they were stock to you?
I suggest more photos, and also posting them at a forum like this one:
TheCJ2Apage.com everything about the Willys CJ2A Jeep
These guys are just a bit obsessive about the minute little details of flatfenders.
And this site is a great one for identifying Jeeps. Good luck!
The Jeep Spotter's Guide on The CJ3B Page