The generator matrix

 1  1  1  1  1  1  1  1  1  1  1  1  1  1  1  1  1  1
 0  2  0  0  0  2  2  2 2a  0  2 2a 2a 2a 2a  0 2a^2+2a  2
 0  0  2  0  0 2a^2+2 2a^2+2a+2 2a^2+2a 2a^2+2a  2 2a+2 2a^2+2  0  2 2a^2+2a+2 2a 2a^2+2a 2a^2+2a
 0  0  0  2  0  2 2a^2+2a+2 2a 2a+2 2a^2 2a^2+2  0 2a^2+2a+2  2 2a 2a^2+2a 2a+2 2a^2+2a
 0  0  0  0  2 2a^2+2 2a+2 2a 2a^2+2a+2 2a 2a^2 2a^2 2a+2  0 2a  2 2a 2a

generates a code of length 18 over GR(64,4) who´s minimum homogenous weight is 96.

Homogenous weight enumerator: w(x)=1x^0+532x^96+2184x^104+3136x^112+6384x^120+229376x^126+10395x^128+7112x^136+3024x^144

The gray image is a code over GF(8) with n=144, k=6 and d=96.
This code was found by Heurico 1.16 in 7.63 seconds.