Bearing, 5/16in balls, suit Norton Steering head race (set34)

Steering head race 5/16in ball bearings, Norton. Set of 34 +1 spare to suit brazed frame Norton. 17 balls go into each race, top and bottom of the steering head (1 spare in case you drop one).
Original part number
9581; A2/521 ; 17714 - Frame head balls (per set 34). Suits all models 1933 to 1962?