A member of Ford’s FE big-block engine family, the 390 cubic-inch block is difficult to distinguished from other FE engines, as many of its components are interchangeable. The 390 is a common FE engine, first introduced in 1961 and produced through 1971 for autos and 1976 for trucks.
Begin by identifying the block as an FE and then compare the casting number to a listing of known 390 numbers. If this doesn’t work, measuring the bore and stroke is necessary. Casting numbers give year of manufacture and the original vehicle model, but they do not identify engine displacement.
Identify the FE block characteristics visually. According to the Fordification website, All FE engines have five valve cover bolts.