RPoston:
I assume that you are referring to a S&W US Army Model of 1917, correct? If it is unaltered then I further assume that you want the period correct USGI holster for your revolver. If so, that would be the Model of 1909 made during 1917-18.
Only one company made those holsters in WW1 for the US Government: Graton & Knight Manufacturing Co. of Worcester, Mass. Their holsters are marked on the body with a large "U.S." encompassed within an oval, and marked "G&K" with the date on the back side of the belt loop.
The photo below of a US Doughboy nicely illustrates the Model of 1909 holster, as well as the 3-cell ammunition pouch on the M1912 pistol belt.
I hope that this information was helpful to you.