Sorry, I actually put these dimensions in the Stallion thread.
I put horizontal slots in mine. Got a beautiful narrow diamond dremel cut off wheel just for this. Lower one is 9/16 from the bottom and the top one is 7/8 from the bottom. It's working well but on my next one I'm going to try 1 1/8" from the bottom for the top slot. That may be too high though. We'll see. The coil sits 1 1/2" from the bottom.