No, The "E" stands for engine, so the bean counters and book worms know that part was originally released for production by the engine division. "A" is chassis, "B" is for body, ect. Service parts have another letter usually for the car line it was intended for, "Z" for Ford or "Y" for Lincoln. The "C" suffix is the enginerring level, C would indicate the 2nd revision from the origonal part. 429-460 heads will fit on left or right banks except those drilled for thermactor.