Lincoln book shows these are Standard Size pistons for'36-39 Lincoln Zephyr and Continental V-12. Last photo shows page in Lincoln Book for reference.
Please check my other auctions. The item "NOS 1936 1939 Lincoln V-12 ENGINE PISTONS Original set 12 86H-6110-A2 Standard" is in sale since Friday, October 25, 2019. This item is in the category "eBay Motors\Parts & Accessories\Car & Truck Parts & Accessories\Engines & Engine Parts\Pistons & Rings".The seller is "djb970" and is located in Fort Collins, Colorado. This item can be shipped worldwide.