As a quick identification, these early double action revolvers have the side plate on the right side of the frame and the cylinder rotates counter-clockwise.
They will have identifying stamps and the serial number on the bottom of the butt.
The military models will be marked as such on the bottom of the butt and used smooth Walnut grips.
The civilian models had hard black rubber with molded in checkering and Colt logos.
The Navy Model and Army model had different logos.
For replica grips, there are modern plastic replicas that look like the originals..........
Sizes / Dimensions; Measuring right panel (vertical not diagonal) 3 5/32” long 1 15/32” wide across center of screw hole 1 29/32” wide @ butt About the Colt New Army Revolver; These grips are used on Models 1892, 1894, 1895, 1896, 1091 and 1903 of the New Army Revolvers and were made in various...
Look inside the crane area. There should be an assembly number stamped there. If there is a capital "N" above or below the number it is a New Navy. Otherwise, it is a New Army. The New Navy used the grips with the word "COLT" at the top while the New Army stocks had a rampant colt. If it is a 38, check the cartridge bores in the cylinder. If they are bored all the way thru, it is pre 1904/5 and used the 38 Colt cartridge with the heeled bullet and outside lubrication (larger bore). If the cartridge chambers have a small lip at the front then it is chambered for the 38 Special and will have the .357-.358 barrel bore. Hope this helps.