 Sizes ranged from 287 cubic inch to 455 cubic inch.This similarity (except the 301 & 265) makes rebuilding these engines relatively easier.This feature also made it possible for Pontiac to invent the modern muscle car, by the relatively simple process of placing its second largest-displacement engine, the 389 cid, into its mid-size car, the Le Mans, creating the Pontiac LeMans GTO.