Chrysler B and RB heads have had several changes since 1958. The 1958-1961 B engine heads used 1.95" intake valves and 1.60" exhaust valves. Four-bolt valve covers were used until 1963. In 1962, the heads used 2.08" intake valves. Six-bolt valve covers were used from 1964 until the last B and RB engines were built in 1978.

A closed chamber high performance head, #2780915, was introduced in 1967 for the 440. It used a 1.74" intake valve. This head can be interchanged with the 1963 Chrysler 300J B engine high performance head, for similar performance results. The closed chamber design of the 1967 440 HP head yielded more performance possibilities than the 1968-1971 open chamber design heads.

The "emission head", used on late 1971 and all 1972 B engines, is casting number 3462346. It featured flatter intake ports. The 1973 casting is similar except they had extra cooling passages near the spark plug hole. In 1974, the change to hardened valve seats enabled unleaded gas usage.

From it's introduction in 1964 until it's demise in 1971, Chrysler offered five different Hemi cylinder heads. All will interchange. The 1964 heads are cast iron. In 1965, the Super Stock Hemi heads were cast aluminum, had two spark plugs per cylinder and were intended for race use only. The 1966 through 1971 Street Hemi heads were cast iron. Even the 1968 Super Stock Darts and Barracudas used the cast iron heads. The new D6 Hemi uses aluminum heads.