GeekDad Puzzle of the Week: Cross Number Magic

More cross number puzzleage. Remember, email your solutions by 10:00 p.m. EST Thursday to be part of the random selection of correct answers and win a $50 gift code to ThinkGeek!
All readers who check out the solution on Friday will receive a gift code for $10 off of their next ThinkGeek purchase of $30 or more. Puzzle after the jump.

This cross-number puzzle has three different solutions that fit the grid. Find them all. In some cases, the same square of the grid can be filled by the same digit in different solutions, but in no case is the complete answer to a clue the same in different solutions. There are no zeros.

Across
1. The sum of the digits is the same as the sum of the last three digits of 6 down.
3. A multiple of 16.
5. The sum of the digits is half the sum of the digits of 7 across.
7. The first digit is greater than the second digit by the same amount (which may be 0) as the second digit is greater than the third.
9. Digits are all different, with none greater than 5.
11. A perfect square.
12. Half of 3 across.

Down
2. (Reversed) A multiple of 9.
3. Sum of the digits equals 16.
4. The number formed by the first two digits is twice the number formed by the last two.
6. Successive digits increase either by the same amount or in the same proportion (i.e., either in an arithmetic or geometric progression).
8. A perfect cube.
10. The magic number.

Find all three solutions and the thus the three different magic numbers (10 down).

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