The pilot bearing is a bearing [in this case a bushing- an after market
quick/dirty fix] in the rear of the crankshaft, into which the [manual]
trans pilot shaft fits. Serves to support the front end of the trans shaft.
Only MT engines had pilot bearings. Since 90% of Olds engines were destined
for AT use, most Olds cranks are not even drilled to accept a pilot bearing.
So, spend another $80-100 to have the hole cut and buy the bearing if you
have a manual trans.
[ Thanks to Chris Witt for this information ]