Jake brake question isx 870

[Sledpuller]

I have a 2004 Mack with a 565hp cm870. I ran the overhead the other day and noticed 3 Jake solenoids. And was wondering why I only have 2 positions for for my jakes. Low and high I assume. My truck uses a single 3 position switch off, low, high. I did a little research and saw that most have 3 positions low, medium,high. I like to make sure I’m getting full Jake operation out out of my truck. Maybe I just have medium and high. But I’d like to make sure all 3 get activated on high.
Anyone have and ideas or insight into this?
Thanks!