Spit/GT-6 starter question

[Aribert_Neumann@magna.on.ca]

On my '71 GT-6 starter motor there is a square on the end of the armature shaft
(end opposite of the flywheel engagement).  What is the purpose of this square,
why would I want to use a wrench to rotate the armature?  I am considering
cutting the protruding square off (shaft protrudes about 3/8 in. out of the end
of the starter motor) to gain a bit more clearance to the headers.