The number defines the heat. 6 is hotter than 7 and determines the gauge of the wire used. The C and F is the length of the body. F is long body or Fredo (Cold). C is short body or Hot (Caldo)
The G is if its a gold connector and the T is for Turbo so a C6TGF plug is 6 gauge wire turbo plug with a gold connector and a long body
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