Angel,

Since you are starting with a 7 you only have to choose 3 of the 4 digits. You can generate them all using the Combinatorial Object Server page that generates combinations, http://theory.cs.uvic.ca/gen/perm.html. Choose all k-permutations, set n = 10 and k = 3. This will give you all permutations of 3 items chosen from {1, 2, 3, ..., 10}. Whenever you see a 10 just replace it by a 0 and you will have what you need.

Penny