here are the sizes for the bolts that go through the rear body mounts. Jon (60-66) looked it up. the part nbrs were taken from the assembly manual and you can see them there.
3771357 No 2 , 3/8 16tpi x 8 1/2" square neck
3771358 No 7, 3/8 16tpi x 5 3/4" square neck
3810759 No 4 3/8 16tpi x 4"
3811750 3/8 16tpi x 5"
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