This photo appears to have been taken in the Pontiac Studio. The presence of a "transfer lug" cast into the block just above the bellhousing and near the ignition coil indicates that this Tri-Power engine is a 421. Though the cylinder head lacks any identifiable casting numbers, such characteristics as the A.I.R. rail, the overall shape of the center exhaust port, and unique cylinder-head bolt at center suggests that it's of '66 model-year vintage. It is quite possibly a pre-production '66 421 that designers used for mock-up during vehicle development.