Got this proof set in a large collection just wondering if i got lucky: http://img42.imageshack.us/img42/5527/img3650y.jpg http://img692.imageshack.us/img692/8950/img3652v.jpg
Your pic is a little small to be positive, but it sure looks like a large date to me. See http://lincolncentresource.com/smalldates/1970Ssmalldate.html
http://lincolncentresource.com/San_Fransisco_Mintmark_Styles.html They can explain it better than I. FWIW, the 1979 S Type 2 mintmark is the same as the 1981 S Type 1 mintmark.
Here is a thread of mine on a different site that should help. http://coinhood.com/e107_plugins/forum/forum_viewtopic.php?17040 The 79 type one mint mark is thicker and clogs more than the type 2, which was thinner and better at not clogging. The type 2 lasted until middle 1981 when it was replaced. Since it was the first mm of the year it was renamed type 1 and the replacing 1981 mm became type 2. 1979 ----Type 1 for first part of 1979 1979---- Type 2 for last of 1979, which is also 1981 type 1 for first part of year 1981-----Type 2 for last part of year, thinner and more open curves than type 1.
