My 3" Model 13-3 .357 has the number 71X** on the crane with an E5 above it. In that number there is an "X". The asterisks are numbers blanked out. On the but of the gun is # AAW02** (last two numbers hidden here). There are no markings on the frame under the crane. An FBI connection has been passed along with this gun, but I don't know if that's true. Is there any clues here to that by these numbers? And any idea when this gun was made?