4 digits serial # mid- to early 70's most were 1 in 48,few and far 1 in 66
1 in 66 would say first year run most were sharon barrels,on the sharon barrel look for a heart ot t/c call it a spade on the underside near the barrel end by the breech=plug.
IJUST GAVE AWAY a fiber optic rear sight ,seem nothing to trade on hand right now
I heardalso if you are lucky to purchase a t/c without a name (MODEL)on like HAWKENS OR RENEGADE some say there were not made by t/c,all my flinter barrel's have no name stamped in them except for thompson center rochester N.H. and all will drive tacks with patch round balls