This particular SD40-2, like all of the other Milwaukee Road SD40-2s, had standard-range dynamic braking, identified by the lack of a contactor access door ahead of the intakes. The "new" 2007 has this as one of the options, so that was one less thing to worry about carving off.
Following the lead of Liz Allen and Dave Hussey, I've decided to make the dynamics on this unit "see-through". Now the prototype isn't completely see-through - you can't see daylight through the grills if you view them side-on, but you can see the dynamic resistor grids immediately behind the intake fins. I wanted to replicate this, so the first step is to carve out the existing dynamic brake intake detail, as can be seen in this photo. The bulk of the work was done with a rotary bit in my Dremel, with cleanup done with a sharp X-acto and files. I need to fill in a small area near the front of the housing on this side where I dug a little too deep with the knife, but luckily, it's not in a critical spot.