We have III, TT, D, S, R, B, U, O, N

Number of words with selection (a, a, a, b)

$$={ }^8 \mathrm{C}_1 \times \frac{4 !}{3 !}=32$$

Number of words with selection (a, a, b, b)

$$=\frac{4 !}{2 ! 2 !}=6$$

Number of words with selection (a, a, b, c)

$$={ }^2 \mathrm{C}_1 \times{ }^8 \mathrm{C}_2 \times \frac{4 !}{2 !}=672$$

Number of words with selection (a, b, c, d)

$$\begin{aligned} & ={ }^9 \mathrm{C}_4 \times 4 !=3024 \\\\ & \therefore \text {Total }=3024+672+6+32 \\\\ & =3734 \end{aligned}$$