What do we know about Stafford?

Gerard:  75 miles from Indianapolis  (The Judgment, I)

Gerard and Richard Kimble's train from the west coast  is going thru South Bend  to Stafford but they get off at some point and rent a car to drive to Stafford  (The Judgment, II) 

RK takes the 8:45 pm  train from Decatur, Illinois to arrive in Stafford at 11:43 pm  (Escape into Black)

Leonard Taft takes the train to Logansport then rents a car to drive to Fort Wayne,  Donna takes a flight from Stafford to Indianapolis and then connects to Fort Wayne.  (Running Scared)

Eckhardt turns onto SR 31 to turn towards Stafford (Trial by Fire)    Indiana 31 runs from South Bend through Kokomo to Indianapolis implying a more central location.

The above clues imply that Stafford is in the northwestern part of Indiana 75 miles from Indianapolis.  The train going thru South Bend implies a more central location while the train from Decatur implies a more western location. 

The below map shows a 75 mile radius from Indianapolis which extends from Twelve Mile, Indiana  thru Monticello (population 5700), northwest of Lafayette and then to the Illinois line.  To pick a specific town, Monticello might be the logical choice although it population is much less than the mythical Stafford.  If you want to say the 75 miles from Indianapolis was only an estimate, then Lafayette is the only town of near sufficient size.  But then again, Stafford is but a mythical town.