This was so heavy with rust I couldn't see a single letter.

Why the spelling Motocycles ?

That is the way the Hendee M C CO spelled it . Initially known as the Hendee Manufacturing Company but  was renamed the Indian Motocycle Manufacturing Company.

Possibly a Thorsen made wrench, as it is well documented they once had a contract for Indian Motocycle wrenches.

Motorcycles were still a very new idea when Indian started making them in 1901.  The word "motorcycle" had not been "agreed upon" at the time, 1901, the first Indian was made. 

Other names for this newly-invented transportation device included Motor Cycle (Marsh Motor Cycle Manufacturing Co. in 1903), and Auto-Bi (E. R. Thomas Motor Car Company, before 1905).