GTS or GSS

I am very aware of the M being in the vin . The fifth digit. For 68 and 69 a-body’s. But in 68 there were M- code dart. There were only 48 or 50 made. So if you know anyone with a 1968 GSS m- code dart . But remember it will have to have a M in the vin tag. Here is what it will look like
LS23M