The stenciling and placards would be in the production drawings or blueprints. There will probably be a few master drawing that show the locations on the airframe with references to the part numbered individual drawings.
NASM Archives should have them on 35mm microfilm. If you don't want the full set of microfilm then get the index to look up the part numbers and then order the specific drawings or reels. Typically the drawings are all over the place and will rarely be on one reel. It's best to get the full set but it's expensive and takes a long time from NASM Archives.
I would bet that you could find the drawings quicker from another A-26 owner or group. Ask the Special K gang or the CAF group that's been doing the restoration work. If they don't have them they probably know who does.
Hopefully someone will have them scanned so you don't have to mess with the film reader printer. Having the films scanned is by far the best way to go. It will pay for itself in time savings alone. Likely not cost effective if all you need is the placard drawings though.
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