The only serialized part on a U.S.G.I. M1 carbine is the receiver. So, it is impossible for the serial numbers on the receiver, barrel and stock to match unless someone hand stamped the barrel and stock.
Davidsons would'nt be the wholesale firearms distributer would it? If so, your friends carbine may be an import. I have never heard that Davidsons was in the firearms importation business.
In case you are unaware, during the late 80's, early 90's, many thousands of U.S.G.I. M1 carbines were returned (imported) to the U.S. from foreign countries. Most from South Korea. The value of these carbines is less than carbines that were not imported.
I really don't understand why since they are both U.S.G.I.. I suppose that carbine collectors being as snobbish as any other collectors, don't anything other than original markings stamped on them. Regardless, if the carbine is an import, assuming it is in decent, shootable condition, it's value would be minimum $400.00. Prices vary by region and other factors such as condition, originality and manufacturer .
There are better carbine forums with knowledgable collectors such as battlerifles.com and Culvers shooting pages.