Headlight question

[66CHEV]

ok so i bought new headlights and an upgraded wiring harness from lmc supposedly for a 66 c10. the plug that is supposed to fit the existing plug doesnt match up. my existing plug from the firewall has two prongs, the one on the new harness has three.

i realize that most likely two of the three new wires need to be wired together and then wired to one of the existing wires but i have no idea which one.

the old wires are one green and one brown. the new wires are one brown, one white, one blue with white stripe. has anyone installed one of these and could help me out with what goes where?

thanks