Ive had a number of guns pass through my hands that had Social Security numbers inscribed on either the receiver or the lower tang. Seems like most of them were from the 1930 to the 1950 vintage.  The most recent one was a couple years ago on a Model 71.  Never had one with a drivers license though. 

As Michael (Twobit) mentioned previously, you do get firearms that may have originally been a carbine and were converted by the factory or on a return to the factory to a standard frame rifle or takedown rifle.  Or, a standard rifle converted to a TD rifle.  If they are in the letterable range they should mention changes in the factory letter, and they are quite rare to find.  Sometimes you may find a rifle with a receiver that has the saddle ring staple holes filled in, have seen that on several 1873’s (most were second models I think) and at least three 1892 rifles–two by all indications looked to be original, the third was not.