I just looked at my fairly early 16 ga. NID star model field grade with cocking indicators. The serial no. is 456xxx. It has the relatively plain buttplate with the horizontal grooves between the screws. I have also seen some with the so-called "ring groove" buttplate. Hopefully Walter Snyder can tell you which is correct, but you might need to give a serial no. range to be sure.

Voting for anti-gun Democrats is dumber than giving treats to a dog that shits on a Persian Rug