Dnn components are usually diodes/rectifiers. They only have two pins, so the pin assignment is never greater than 2. Hunt around for either little 2 pin black surface mount components (SE/30 may be too old for those to have been around yet) or little through hole components with an orange/glassy body, although they might be matte black with a silver stripe on one end. If through-hole, they'll be about the size of a 1/8 watt resistor most likely.

My SE/30s are sitting in the attic with their capacitors removed, so I do not have hands on experience with this issue (and hope I never do, yikes) but it sounds like some of the SCSI chip signals are protected by diodes, probably to avoid reverse biasing the I/O pins.