Hy RAK, that would depend on the engines compression ratio, anything above 9 to 1 would probably require it, basically the higher perfomance engines. Interestingly as an engine gets older, and carbon builds up in the combustion chamber, the compression ratio rises, and the engine will start to "ping" on regular grade gas, but not on premium. The 327 did not come out until 1962, so I'm assuming you or someone else swapped it into your truck.
