Yes...they were sold aftermarket. I don't know if they shipped on any regular production models but probably were on some special models. They use the same stocks that fit any King Cobra from that era and any Mark V Trooper or Lawman.

 

As above, some special limited edition versions of the Anaconda shipped with wood grips, and Colt sold them as after market accessories.

The Trooper Mark V, King Cobra, and Anaconda shared the same size and shape of grip frame so grips interchanged between the three models.
Some of the grips were apparently either a hard wood or very light walnut with little figure, some were walnut, but usually in a light color.

These are what they look like......