The generator matrix

 1  0  1  1  1  1  1  0  1  1  1  0  1  1  1  X  1  1  1  1  0  1  1 2X  1  1  1  1  X  1  X  1  1  X  1  1  1  1  0  1  1  1  1  1  1  1  0 2X  1  X  1  X  1  0  1  1  1  1  X  1  1  1  1  1  1  1 2X  X 2X  1  1  1  1
 0  1  1  2  0 2X+1  2  1  0 2X+1  2  1 X+2  X 2X+1  1  0 X+1 2X  2  1 2X+1 2X+2  1  X 2X X+1 X+2  1 X+2  1  2  X  1 2X+1  1  X X+1  1 X+2  0 X+2  X 2X+2  1  1  1  1  1  1 X+1  1 X+1  1  X  0 X+2 2X+2  X  0 2X  X 2X 2X+1 X+1  1  1  1  1 2X+2  2 X+2  2
 0  0 2X  0  X 2X  X  0 2X  X  0 2X 2X  X  0  X  0  X 2X  X  X  0 2X 2X 2X  0  0 2X  0  X  0  X 2X 2X  X  X  0  0 2X 2X 2X  X  0 2X  X  0 2X  0  0 2X 2X  X 2X  X  X  X  0  0  X 2X  0  0 2X  X  0  X  0  0 2X  X 2X  X 2X
 0  0  0  X  X 2X 2X  X  0  0 2X  0 2X  0 2X  0  X 2X  X  X  X  0  X  X  X 2X  X  0 2X 2X  0  0 2X 2X  X 2X  0  0  X  X 2X  0 2X  0  X  X 2X 2X  0  X  0  X 2X  0  X  0  X 2X 2X  X  0  X  0 2X 2X  0  0  X  0 2X 2X  X  X

generates a code of length 73 over Z3[X]/(X^2) who´s minimum homogenous weight is 144.

Homogenous weight enumerator: w(x)=1x^0+570x^144+144x^153+8x^162+6x^171

The gray image is a linear code over GF(3) with n=219, k=6 and d=144.
As d=144 is an upper bound for linear (219,6,3)-codes, this code is optimal over Z3[X]/(X^2) for dimension 6.
This code was found by Heurico 1.16 in 55.3 seconds.