Secondly, the date code badge cast in the head tells a story all its own. According to Johnson, early engines ('93-94) are good baseline engines, whereas Cadillac designers introduced a new manifold for '95 engines. For engines made in 1996, they introduced a new throttle body. Now here's the real catch: find a '97-99 engine. They've got hard-chromed valve stems. Cadillac redesigned the Northstar for 2000. While it's similar to the earlier units, no earlier parts fit it, it has huge intake valves and runners (a boon), but smaller exhaust valves and runners (a bust). The result, according to Johnson, is a poor intake/exhaust ratio.