The 466 mechanical has an inline pump with six hardlines exiting it and going to the injectors. It has no ECU and no diagnostic connector.
The 466E has a modular pump, with a single high pressure line. It has a sizable ECU mounted on the drivers side of the engine at shoulder height. It also has a valve cover that integrates the intake manifold (ie, there is 4 inch hose coming off the intercooler and going right into the valve cover. It will also have a grey 6 pin diagnostic connector under the dash by the drivers right knee.
"You can finally say you have enough horsepower when you leave two black streaks from corner to corner"
(Mark Donohue, famed TransAm driver)