NI would still like to see if there is a way to date this shotgun. Value of a single shot would be $35 to $75 for a large guage, but there are fools out there who will pay 2 or 3 times that for a.410 even though they can buy an equivalent new gun for $89.95. This is a store-brand made by Crescent Fire Arms, Crescent-Davis Arms, Iver Johnson, or J. Your numbers are not serial numbers, but manufacturer batch numbers and cannot be used to date the guns. I have also tried to find a value for mine with no success yet. The serial Number is lower which should mean that it is an older firearm. NI have an Excel 410 ga single shot also. Lately during the filling cycle water hammer is occurring.
SOURCE: I have freestanding Series 8 dishwasher. Value depends on condition, but old singles seem to bring $50-$75 if they are fully functional. The Excel trade name was used by Iver Johnson on single shot shotguns sold by Montgomery Ward c 1900 - 1950.