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It does decode as 1982... and as you said they only started in 1983.
Mine was build in Nov 82 for 1983 production year and the VIN does indicate that as a "D" in the VIN 10th Position.
Its probably a conversion as your VIN decode it as a Coupe. A sign that it would be a conversion would be the absence of the damper (mini shock absorber on the engine carrier which is also different from the other models). Off course having one would not say that it is not a conversion either as some conversion were well done.
Below is a picture of the proper bracket on an updated 3.2 engine, she had a major face lift at some point.
As for the books, the more reference the better: Bentley, 101 Project, Porsche 911 Performance Handbook (1963-1998), Tech & Spec guide, How to Rebuild and Modify your Porsche 911 Engine (even if you are not going to) and yes... Haynes book. All the books have mistake in them (Bentley, Haynes and Wayne's one too), so the more that you have to cross reference the info, the better. Also when I had the engine out, for a specific procedure, the Haynes one had the best photo. It's in the car with me all the time. They are all available here at PP:
PelicanParts.com - Porsche Catalog > Pelican Parts Bookstore > Porsche Technical Books & Manuals
Have fun
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Who Will Live... Will See
83 911 Production Cab #10, Slightly Modified: Unslanted, 3.2, PMO EFI, TECgt, CE 911 CAM Sync / Pulley / Wires, SSI, Dansk Sport 2/2, 17" Euromeister, CKO GT3 Seats,
Going SOK Super Charger