Yep, he's totally correct.
N.orth A.merican S.pecs
It's a term for the overall truck, not specifically the engine. There were a lot of design changes needed to make the Defender meet US laws regarding emissions controls and impact standards. Most obvious is the external roll cage and left-side steering, but there are other more subtle differences as well.
My oil line fix
My 100k stopped odometer fix
Brace for impact, I'm in a "modifying mood". Massive thread count inbound.