[1950Mercury]

Trying to decipher what I have. Working on 66 GTO 4 speed console car none A/C rally gauges. The under dash wiring is M&H.. Looking at there website it seems they do not offer a harness for a 4 speed car with gauge package. Closest is automatic w/gauges. Is there one offered for 4 speed console GTO's with gauges? On the left side of the harness there are 3 pairs of wires with 2 wire each and a plug at the end. 2 purple 2 green and 2 orange. I figured the purple are neutral start. Although I don't 66 manual 4 speed had a neutral start. Anyone know what the other 2 pairs are for? Also the diagram refers to a master switch and a master relay.. Where are they located and what do they do? Is that for A/C cars only? I appreciate any input.