To find the number of different 8-letter words using the letters of the word "SYLLABUS," we can use the formula for permutations of a multiset, where some elements are repeated.

The correct formula is:

\[ \frac{8!}{2! \cdot 2!} \]

This is because there are 8 positions, but the letter "S" appears twice, and the letter "L" appears twice. So, we divide by \(2!\) for each repeated letter to correct for the overcounting.

Therefore, the correct answer is \(\frac{8!}{2! \cdot 2!}\)