My son-in-law just inherited a S&W Model 60 no-dash from his grandpa. He sent me pictures and it shows MOD. 60 on the crane but the serial number starts with ABJXXXX. Thought that was not right, but just read somewhere on way earlier post that the no-dashes were produced well into the 80s along side the 60-1s, and some with with 3 letter serials too. Any comments?