The generator matrix

 1  0  1  1  1  1  1  1  1  1  1  1  1  1  1  1  1  1  1  1  1
 0  1  1  a a^6*X+a^2 a^3 a^6*X+a^4  0 a^5 a^6*X+a^6 a^6*X+1  X  a X+a a^6*X+1  X a^5*X+1 X+a a^6*X+a^2 a^5*X+a^2 a^5*X+a^2
 0  0 a^6*X a*X  X  0 a^3*X a^2*X a^5*X a^4*X a*X a^6*X a^4*X a^2*X a^2*X a^5*X a^4*X  X a^3*X a^6*X  0

generates a code of length 21 over F8[X]/(X^2) who´s minimum homogenous weight is 135.

Homogenous weight enumerator: w(x)=1x^0+1344x^135+161x^136+2240x^140+4480x^143+140x^144+15680x^148+8512x^151+84x^152+91x^160+35x^168

The gray image is a linear code over GF(8) with n=168, k=5 and d=135.
This code was found by Heurico 1.16 in 0.0591 seconds.