The 265 is unique in the way that it actually fits into an AD truck. It had no side motor mounts so it front mounted and it's bellhousing had the rear motor mounts on it both of which are like the inline six but NOT interchangable. The left hand exhaust manifold has a dip in just the right place to clear the steering box and the exhaust outlet is towards the front which also clears the gearbox. When done right it does look like a factory install but no V8 was offered in the AD style truck. The 265 was offered from 55-57 in trucks but just 55 & 56 in cars. If the oil filter is in a canister mounted to the T-stat housing it's a 55.

Evan