It's been a while since I bought the electronic ignition unit that's in our NFN 300 petrol bus but I'm pretty sure it's one of these units that are used on the D204 distributer in a Bedford bus, see below TradeMe listing. Powerspark Electronic Ignition Delco D200 6 cylinder Distributors +ve Earth K26PP www.trademe.co.nz/a/motors/car-parts-accessories/vintage-parts/electrics/listing/3545771314?gclid=Cj0KCQjwgMqSBhDCARIsAIIVN1WFQPcn9qE6Vg1YeAeSPRszyrOh9tFY-ggSc941Z_NFGrngbl9yxUIaAq6qEALw_wcB&gclsrc=aw.ds