*********. The Lightning never had a "Mustang-sourced V8".
Gen 1 had a 351W which was never offered in a Mustang those same years. The Gen 2, which had the side exhaust they mention, had a 5.4L 2V engine, which was never offered in any Mustang- ever.
You're definitely correct on the 5.4. But as I recall, my 2001 Lightning was a 3 valve.