The South Bends didn't have "bushings," they had Babbit metal bearings. They could hold the same tolerances as a lathe with P7 bearings (0.0002"). "Babbit" refers to not only the type of bearing (which looks like just a bushing), but also the specific alloy. 

Machines with Babbit bearings needed to have a constant flow of oil (in a drop or two per minute) flushed through those bearings. There is a real need to have a constant flow of oil through the bearings on a South Bend - those oiler cups need to have oil put into them EVERY time the lathe is started.