they are Nippon Denso and coloured Grey, they can be got from 70/80's Suzuki's
EG, a GT380 will yield 3 of the single outlet coils
and GS1000 will yield two of the double outlet coils,
genuine ND ones are grey so beware of cheap aftermarket replacement's, sometimes they are black.
The ND ones have moulded in HT leads, but they can easily be replaced, just cut the wires flush with the body using a junior hacksaw, then with a 3mm drill in a cordless drill/driver, dig down the outside area of the now flush HT lead to loosen thing up a bit, next use a pair of tweezers to "pick" out the remnant's of the cable and its insulation, and you arrive at a clean hole with a steel spike in the middle, get your new cable, pierce the end of the conductor with a gimlet and then coat the outside first 20mm or so with Araladite and place it down the hole onto the spike, screwing it down (althought its a spike not a screw thread) until well seated, build a fillet of Araldite and allow to set, JOB DONE.
CLEM