Yes, Im a newbie, but if im not mistaken... was there an available 3.0 V6 engine available for the US 240sx...from 90+? Not from Datsun...Nissan...I was wondering, please help

Nah, the 89-90 240sx had the KA24E, a 135hp single cam engine. the 91 and up 240SX had the KA24DE, a 155hp double cam engine. There was no V6 in the 240SX.
You might be getting it mixed up with the VG30DE or the VG30DETT which were both a V6 but came in the 300ZX.