It was but all we are talking about is the engine code on the build plate. If you read through the list of RPO codes I posted earlier they all refer to the 3800 V6 motor. The ecotec is just an evolution of the older 3800 Buick V6. Ecotec is what Holden called this motor down here, in America the Ecotec is something completely different and what we know as the Ecotec they call it the L36.
How many Commodores have GU4 for the axle code, what does it mean? All it means is 3.08 ratio but it doesn't tell you if it's a standard open diff or LSD.
Guessing why and how Holden/GM uses RPO codes is a mystery.
An earlier post in the thread describes the differences quiet well between early ecotec motors (VS) and later (VX/VY). All that info is still correct and relevant.
Sometimes it just pays to not overthink these things.
All ecotec motors are basically interchangeable, there were minor changes/improvements made during the production run. Head castings (cracking), intake manifold PCV location, EGR etc