First mass-produced domestic DOHC 24V V-6?

[440Magnum]

DOHC = two camshafts per cylinder head, regardless of how many cylinder heads there are. For example, the Chrysler EDZ 2.4L (inline 4) is a DOHC, but the 3.5L v6 (1993-2010) is a SOHC. Both have two camshafts total, but its the number per head that matters.