The serial number on the stock, if marked, will be under the trigger guard tang. Ithaca was clearing our the double guns at this time--cleaning out the bins as it were. Guns were being offered at 'deals' and a variety of subtle differences in configuration are seen. Your gun has all the options except a vent rib.
Your statement about 'cleaning it up' frightens me a bit. Your gun looks to be in new condition. Dust it off, lube the rub places with a gun grease and enjoy it as it is. You have a very nice gun just the way it is!
