The three things that engage the torque convertor are the input spline which rotates, the Stator support
that keeps a part inside the convertor stationary, (hence the name Stator) and the two front pump lugs
that pump oil through the trans. The two splines are fine just about with any gap, but the pump gear
is about 3/4" thick and needs to be driven with as much of the two cutouts in the nose of the convertor
without pushing it up against anything causing wear, chips, shavings, etc. It needs to operate in a "Free"
state so the gap is just a close figure. I had a friend with a Buick GS and while no gap didn't hurt his trans,
it kept pushing on his crank and ate through the thrust bearing and into the block! What a Hot Mess! Maybe
his convertor ballooned too adding to the failure.