HEI Ignition Performance Distributor

Slightly less cost for a "ready-to-run HEI" w/o integral coil ($45) and an external e-core coil ($20). Slightly more wiring, but that is nothing compared with dealing w/ clearance issues.

Re "The module is not the same as a GM",
The module inside the $45 one looks like a standard 4-pin HEI module, used on early GM's. Later GM's used other modules. The 8-pin module w/ Metripack connectors is best for several reasons, and used in 85-95 GM "small cap, computer distributors" w/o integral coil.