Just realized this is an ANCIENT thread...whoops. Leaving the answer for any who might stumble upon it.
We have a feature class named Townships, that we use as our grid for mapbooks. In the attribute table, for each row we have a "Township", "Range", and a "MapName" column. Then we simply add two dynamic text objects like so:
The MapName column is simply the Township and Range together, separated by a hyphen. Overly redundant, but it has its purpose.
So, if you have the township and range in your attribute table, just add the labels above, substituting your column names. If you don't have the township and range, add the columns to your table.