Haven't found any emblems yet, thinking about a simple Cummins "C" above the bowtie 20 or marker light. Another possibility is to put it where the Banks sticker is on my cowl (I found it ironic to put that sticker on it when the ToroFlow was under the hood).
I might even run it without Cummins emblems as there are already 3 on each side; 4 wheel drive, bowtie 20, and custom on the door.
Also thought these ones were pretty cool too:
