I'm aware of a couple of directories that might help you.
1902-03 Johnson's Business and Professional Directory of Indiana, p. 132 Gas City Business Directoryhttp://archive.org/stream/johnsonsbusiness190203wash#page/n1...
1895-96 Polk's Ind. State Gazetteer & Business Directory: I don't think this is online; they have it at the Indiana State Library and many smaller libraries in Indiana.
Here is a list of some other Indiana directories:http://www.naturalizationrecords.com/usa/in_citydir.shtml
The Marion Public Library could help you with other Grant County directories.