That's what I have read, as well. An 18 inch extension was added to each inner wing to allow space for additional wing fuel tanks; the wingtips were squared off, as Thomas stated, to improve the roll rate; IIRC there was an autopilot fitted to relieve the pilot on long flights as well as armrests on the seat; a C-series R-2800 was fitted, ( I don't recall the P&W model, but I could look it up.) and on later production blocks, stub mounts for HVAR's were fitted. One detail that might or might not be correct on the Academy and/or Revell 1/48 kits to look for is the P-47N had no shroud over the back of the instrument panel, so you can see the gauge housings and wiring from above,
Mike