What model of US issue Colt DA revolver are these stocks from?

[M1Garandy]

Came into a pair of walnut Colt stocks. I thought they were for a New Service when I got them, but they are a little smaller. After cleaning off the residue from three different kinds of tape, I've found some markings.

The right stock is marked RAC (I think, the script is hard to read) in a box. It is marked either 6666 or 1666 (or depending on which way is up, 9999 or 9991 on the inside in pencil.

The left stock has an oval cartouche that I can't quite make out and looks to be stamped 1896 above that. It is marked R.A.C. on the bottom and 9999 or 6666 on the inside in pencil.

I'm thinking these are off of a military Colt DA .38 revolver, but which of the many iterations of martial Colt revolvers would they have come from?

Also, the stock screw is missing, would this be the correct screw: www.gunpartscorp.com/Products/195390D.htm

Thanks.