All F53's past about 1999 have the 6.8L, no matter what chassis capacity and tire size. Lots of us have done the 5 star tune and liked it. On our Canyon Star the only issue was surging when on cruise when it downshifted two gears, I believe they have that fixed with more recent versions.
Stewart, Brenda and kids
2008 Newmar Canyon Star 3410, now at a new home
2006 Roadtrek Versatile 210