'75 chebby module w the (4) 1/4" male terminals. (B) goes to switched 12V (C) to coil neg primary. Other 2 go to dist & must b polarity correct. Mount on a piece of alum w dielectric grease between the 2 for heat dissipation. Can mount/hide it under the dist by fabbing a plate & someone offers that plate but it's pricey & it's easy to do yourself.