The shank design number is visible as 5690?, the only similar shank design number is 56904. The diameter of the shank was reported as about 6 3/4 inches which matches the "D" shank blade design. The 56904 is for D shank blades. Possible models that used the 56904 where the following per H/S manual 130: 6487A, 6505A, 6523A, 6529A, 6531A, 6533A, 6535A, 6539A, 6547A, 6593A, 6597A, 6601A. The reported maximum blade width was reported as about 11 inches, which by looking at the blade width specifications it eliminates all but the 6487A, 6523A, and 6547A. These were all used on the P51, with the 24D50 propeller. There is evidence of the remains of a blade cuff still present on the inner portion of the blade, so that would be either the 6487A and 6523A, which used blade cuffs, and had full round blade tips.
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