Bridgeport X&Y Screw Replacement Bearings

Does anyone know what the specific bearings are for a Bridgeport M-
Head 9x32 screws? I am designing my motor mounts ect, and I need to
buy replacement bearings for both X and Y screws. I have installed
ball screws but am sure they are a direct replacement for the acme
dimensions. The existings bearings only have "Fifnir" on them with
no numbers for reference. What I really need are specific
manufactures and part numbers so I can get full specs to design the
whole thing in 3d.
Mark