as the 383 is a B engine while the 440 is an RB one. The 440 was the last of the RB line, boring out the 413 V8 for a larger displacement. Importantly, you could get the 440 in a high-output ...

This was a line that began in 1958 and lasted for 20 years, with the largest hitting the market being the Mopar 440 in 1966. However, there was not just one version of this 7.2L V8 engine available.