It should be O-105 which is the most common (R1) for 1807 I bought the same coin two weeks ago ;-) Obv: 1 in date is joined to the curls Rev: See the lump between S of STATES and O of OF? http://www.coinfacts.com/half_dolla...s/1807_half_dollars/1807_half_dollar_o105.htm
@BigTee44 - My coin has the same crack right above the date but it's not mentioned in the description of O-105. So I am not sure if we can refer to that crack as a die marker...