SEE PLUG NOTES !! - 1/2 & 3/4 Ton Models - External Mechanical Type FD brand. 6 pin female, round, green plug. External mechanical type. - External - Mechanical Type FD brand. 6 pin female, round, green plug. External mechanical type. - External mechanical Type w/ 50 Amp Alternator FD brand. 6 pin female, round, green plug. External mechanical type. -