NISMO/LE Audio Package question...

I just purchased a 2005 4X4 NISMO King Cab Frontier and it came with the NISMO/LE Audio Package. This is the 6 speaker, 6 CD/MP3 player with the audia controls on the steering wheel. The saleman said it was the Rockford-Fosgate Stereo but there is nothing on the head unit or anywhere else that identifies it as such. Does any one know if it is in fac the R-F Head unit? When I look at the options sheet the R-F system is offered only in the Crew Cab model with 10 speakers and a sub woofer. My system says 6 speakers and nothing about a sub woofer (although the salesman claims it has one!). Thanks for the input/clarification!