Step 1: Critical points
\(f'(x)=6x^2-30x+36=6(x-2)(x-3)\), so \(x=2,3\).
Step 2: Classify
\(f''(x)=12x-30\). At \(x=2\), \(f''=-6<0\) (local max). At \(x=3\), \(f''=6>0\) (local min).
Step 3: Values
\(f(2)=16-60+72+40=68\) and \(f(3)=54-135+108+40=67\).
Difference \(=68-67=1\).
Final Answer:
The difference is \(1\), option (D).
\[ \boxed{\text{(D) }1} \]