Notice how GM calls it a bearing.......right on the GM box .
PIC
https://s26.postimg.org/61unuc8g9/Crankshaft_Clutch_Pilot_Bearing_GM_NOS_412562.jpgYou should be able to find one on ebay .
When you get a new one a magnet
SHOULD NOT stick to the bearing .
They are made of Oil Filled Sintered Bronze .
PIC
https://s26.postimg.org/it8u0uxnt/Clutch_Pilot_Bearing_Sintered_Bronze_GM_NOS.jpgDo
NOT polish or use sandpaper on the new bearing .
That will smear the pores on the bearing and then it will not release it's built in oil .
George
'54 3600