Nice, but I like the revamped tail section on Sentinel Chicken's version:
How it's supposed to look all opened up:
Detailed description to go with the above:
This illustration shows the changes that I've surmised might have been made to the S-3B to transform it into the definitive US-3B transport:
1. Fuselage stretch ahead of and behind the wing.
2. Reprofiled aft fuselage to accommodate the aft loading ramp- I moved the fin and horizontal stabilizer upward to provide overhead clearance when unloadding.
3. Clamshell doors on the aft fuselage hinged at the upper line. These open to reveal the stowed loading ramp with then extends. This way the entire aft fuselage doesn't have to be widened and it can keep the basic lines of the body. Downside, though, it's not exactly conducive to opening in flight for air dropping (though the clamshell doors on the C-141A/B were openable in flight).
4. The increased weight of the aircraft would have necessitated a tougher landing gear. The Viking's landing gear is based on that of the F-8/A-7. For this version, I thought that perhaps twin wheel mains that folded into BAe-146-style fuselage sponsons could handle the weight.
5. Removal of most of the ASW mission specific equipment- the wingtip ESM pods, most of the antennas on the fuselage, the MAD boom, etc.
6. Relocation of the heat exchanger outlet from the aft fuselage to the upper part of the aft fuselage aft of the wing.
7. Crew entry door on the aft left side and extra side window behind the cockpit.