[elmariachi]

There is a perception that this stuff should bolt up and fit out of the box and that's just not the case. Spacers, shafts, etc aside, nothing should be taken for granted. My TKO slid into place and bolted up but we used some yellow paint to confirm whether or not it was touching and it was. So we removed the input shaft and had it machined down 3/16" and beveled.

You are facing removing the tranny anyway to inspect the internals so first step after removal would be to measure from the rear BH mounting face into the backside of the seated pilot bushing or bearing, and compare that to the distance from the trans mounting face out to a perpendicular line across the shaft tip. You want the tip of the input shaft to be no deeper than flush with the back of the pilot bushing/bearing once its installed.