How Many D MM Locations....

In the past (not sure when) MM were added after the die was made, so the mint mark could move around and even have RPM. These days, the MM is added when the die is first made.

Check out this site:
http://www.coppercoins.com/
On the home page on the upper left you will see:
search the site!
die variety search
FAQ/education search
news article search

Choose the die variety search and choose year 1960 (you will need to do the year twice) MINT D VARIETY mint mark variety
and you will find what you are looking for.

The position of the mintmark on any given coin is not in itself any cause for specific collectibility. It's whether or not the mintmark is doubled that makes a coin particularly collectible because of the mintmark. Position of the mintmark is merely used to determine whether any given repunched mintmark is from a particular die since the position is the one thing that is unique to each die, yet remains in the identically same position on any one die throughout the die's life.

southsav - coppercoins.com does not belong to Coop. It is my website.

Fuzzy - Almost correct, but not. Up until and including 1989 cent dies, the mintmark was punched by hand after the die was finished. Starting in 1990 the mintmark was on the epoxy master used to create all the master dies. It is not applied to the die after the design is placed onto the die - it is done at the same time.