Views showing, on the right, the long, single-slot "banjo" used to carry the changewheels. At the 8 o'clock position, relative to the end of the spindle, can be seen the hole used to mount a simple 5/8"-diameter by 21/2"-long "reversing stud" that allowed a 32-tooth flanged changewheel to be incorporated into the gear train to allow the generation of left-hand threads. The stud was retained by a "blued" square-headed bolt (of the same size as those used to lock both saddle and top slide) threaded into the casting near the backgear handle and bearing directly against a dimple in the shaft.
On the left the fine-feed compound gear set is in place.

To help beginners identify the fine-feed gears the pair on the banjo arm were clearly marked: compound gear 1 to 5 (with 110/20T) and, on the leadscrew, a single gear marked  turning gear 105t. With these and others gears in place the finest feed was set at 0.0028" per revolution of the spindle.
Note the original South Bend drive system with a V-belt pulley on the motor driving a narrow flat pulley on the "non-adjustable" type of countershaft.