Parka liner is from a m65 parka. Modeled on a size 40 dress form. Please examine the photos carefully. The m65 liner is a size small. I do not see a size on the m-1951 shell.
Here are measurements for the m-1951 parka shell layed flat without the liner. Pit to pit: 26 1/2 inches. Center front to hem: 32 inches.