The generator matrix

 1  1  1  1  1  1  1  1  1  1  1  1
 0  X  0  X 3X 3X  0  X 3X 2X 2X 2X
 0  0  X 5X 3X 2X 4X 2X  X 5X  X 4X

generates a code of length 12 over Z7[X]/(X^2) who´s minimum homogenous weight is 63.

Homogenous weight enumerator: w(x)=1x^0+90x^63+126x^70+2058x^72+54x^77+72x^84

The gray image is a linear code over GF(7) with n=84, k=4 and d=63.
This code was found by Heurico 1.16 in 0.00114 seconds.