An auto trans does not have a pilot bushing. The snout of the torque converter centers up in the large counterbore behind the bushing. On small block V8's, the automatic trans crankshafts have a smaller hole than the std. trans shafts, and if one of those shafts is used with a manual trans, a smaller OD pilot bushing must be used. It's possible that the late model sixes are the same way. To get the bushing out, just thread a 5/8" diameter tap into the bushing and keep turning once it bottoms out. The bushing will walk itself out of the crank. It ruins the bushing, but it's trashed anyway if the trans won't fit into it. If you have access to a good selection of chucking reamers, it would be possible to ream the existing bushing a few thousandths larger than the trans input shaft. Drill bits are not accurate enough to cut precision holes.
Jerry


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