There isn't any polish on "Sierra Sue II", it is all factory-original clad finish (both shiny and dull finishes, as per original). Note that throughout its stay at Oshkosh, they even left the exhaust stains remain.
This photo on Flickr sums up quite well the amount of wartime authenticity and originality of "Sierra Sue II". Non-polished metal, original WWII-period aluminum watermarks, remanufactured original WWII-period spec rivets in all of their original period-correct finishes (silver anodized, blue anodized, and yellow iridite), hand-painted nose art, factory-original primers and paints (not the modern look-alike paints seen in other restorations), a P-38 mirror mounted to the canopy (as done on the aircraft when in Theatre), much of the stencils across the exterior of the aircraft were applied using original factory ink stamps, the correct N-9 gun sight is fitted (not the common K-14), the original and working WWII radio, and of course so much more.
https://www.flickr.com/photos/126942697 ... 2/sizes/k/And of course the coolest thing about all of it is that it is a combat vet survivor, not a data plate rebuild, and is restored in every detail to be as it originally looked in 1945 (weathering continues to be added over time - as I recall Paul Ehlen, the owner/pilot, mentioning, when he flew it into the Aircorps Aviation's open house some months back, when it had been raining prior to it arriving, when he taxied in and shut the engine down he mentioned to Erik Hokuf that they now had the mud in the wheel wells - adding to the extra level of wartime accuracy). Of course everyone has their favorite restorations, but this is the closest anyone has come to presenting a restored North American Aviation product as if it had just come out of 1944/45. Unfortunately I don't think the Oshkosh judging gives extra points for most of the type of authentic factory-correct details seen in "Sierra Sue II", like the factory overspray and streaks in the primer, where, as per original, some parts were dipped in primer rather than sprayed.
Also, the lady in the back of the PB4Y is Lindsey Goss, a warbird restoration and maintenance veteran and a very integral part of the GossHawk Unlimited team. As I recall, she was put in the spot of managing the trip to and stay at Oshkosh for the PB4Y.