4-Prong to 2 -Prong Ballast?

[bordin34]

I am switching from a 4-Prong to a 2-Prong MSD ballast resistor. What I need to know is whether the top of the 4-Prong was the one I needed for it to run or if it was the bottom of the 4-Prong.

[Chryco Psycho]

The Blue & brown wires are used on the 2 prong the green/ red wire is not used