Just got this beauty and it is marked U.S./L.G. & Y./WINDSOR VT on the lock plate which is maker Lamson, Goodnow and Yale
I'm pretty sure the color/stain is original and all the metal parts are inspector stamped (V or K or G or S or H or R) and the cartouche is stamped on the left side of the stock and is faint but there.
Here is more info on the gun
Left side of barrel at rear is marked "VP Eagle's head" in a line on flat with "M.L.H. STEEL" just below. 3 bands each being marked with a "U" rear two also marked with an "A". Inside flat of hammer is marked with a "G". Three position folding rear sights marked 1x 3 & 5 with a fixed front
In 1855, E. G. Lamson, A. F. Goodnow and B. B. Yale joined together to form the Lamson, Goodnow and Yale company. Together they purchased the bankrupt Robbins and Lawrence Armory in Windsor, Vermont, to make guns. The Lamson, Goodnow & Yale Company of Windsor, Vermont and Shelburne Falls, Massachusetts, received two contracts from the federal government for a special Colt model 1861, .54 caliber rifle musket. The company delivered nearly 2,000 guns per month from September 24, 1862, to December 10, 1864, for a total of 50,000 arms during the Civil War. Parts were interchangeable with these and Colt musket parts. These arms were marked on the lockplates in front of the hammer, with an eagle over "U.S.," and "L.G.&Y" over "Windsor Vt," in two lines, under the bolster, and were dated behind the hammer, 1864. During the Civil War, the company was also one of the largest U. S. cutlery manufacturers, employing more than 500 workers at various times. The partnership dissolved after the Civil War