HEI style distributor cap
I think he meant HEI
style as in with the male connectors for the wires at the distributor. You'll get a more solid/reliable connecton at the distributor. I havent had any problems with it, but it is something that could be improved upon (from stock).
Stock - Female @ dist
Magnum/ 'HEI Style' - Male @ dist
And if he did mean HEI ignition, i think i gotta link for that too. Hate to say it but GM did have their ignitions down with HEI, Chrysler wasn't the best and most reliable with their ECUs. 2cents