I know of no reason - nor i, and that's why i went out on a limb with the thinking
it's a four bolt cover, which matches the 3sp muncie in my '68 book. but the input shaft/retainer matches the warner, in that, the splines extend into the retainer
mo better pics, with 'visible' small hole
http://my.opera.com/rednate/albums/show.dml?id=870462
