A/b switch for dirty Shirley mod

[chawonkey]

I have a dirty Shirley mod that's in the works and wanted to get an a/b box so I can switch between the high and low inputs. I read where all you need is a regular a/b box and somewhere else where you need an a/b/y box and when switching you must go from a to y to switch between the inputs. Not sure y? Can someone please confirm if this is correct or not?

 

[RACKSYSTEMS]

A/b y box a or both. Or I have a box made up for this I could sell you.