New ignition switch - 3 wire to 4 prong ????

[bdsii]

Greetings! I am way out of my comfort level here but I suppose this is how you learn. I want confirmation/help before connecting this to prevent problems. After doing a lot of searches on here and the internet I have made progress. For my 1999 DCS 36 golf cart with headlights, I want to swap out the standard switch for a Harley round style key and switch which has three wires coming out of it and it controls the lights also. The problem for me is that the original switch has four prongs on the back. From research I believe that the prongs I and B are for the on/off portion with the L and B1 prongs are for lights. My new switch has 3 wires, a solid red, a red with black stripe and a red with gray stripe. From my basic understanding of a multimeter, I confirmed 38.2 v on Wires going to I and B and 12 v on wires going to L and B1. I also found that on the new switch, the red and red/black have continuity in the on position but the red/gray does not. In the lights on position, all three have continuity. So I am thinking the red/gray is for the lights. I believe that prong B wire is positive and prong I wire is negative and prong L is negative and prong B1 is positive. So......would solid red go to I (neg) and red/black go to B (pos) ? If so, where do I connect the red/gray and the prong L wire and prong B1 wire ? Due to the different number of wires, two of the old switch wires are going to have to connect to one of the new switch wires. I have looked at the diagrams but can't make sense of them in my application. Help ?