Well, I found out the rear bearing is original. Also, taking the screws out was a PITA. I ended up having to push the brushes in to clear the rotor without removing the brushes and rectifier.
I measure 15mm ID x 35mm OD x 11mm W for the rear and 17mm ID x 52mm OD x 16mm W for the front. The front bearing is a KOYO 437. The rear is WBD 6020D. Looking up the numbers on the small bearing, I get this;
Ball Bearing
Dbl. Sealed
For:
Bosch ER/EF, IR/EF, Delco AD230, AD237, AD244, CS130D Series IR/IF (S.R.E.); Hitachi, Mitsubishi, Nippondenso (D.E.); Lucas Generators (D.E.); Nippondenso 3.0kW, 5.5kW OSGR Starters (Armature)
Replaces:
Bosch 1-100-900-000
Delco 10475023
Lucas 54160090, UMB109, UTB100
Ref. No. 6202
Dimensions:
15mm ID x 35mm OD x 11mm W
AMSCO#: 333RR
WAI#: 10-3042-4
ACE/ACCURATE#: A-6942-2S
OEM#: 949100-3330, 949100-4370, 949100-5010
FITS: NIPPONDENSO ALTERNATORS (D.E.)
DIMENSIONS: 17MM X 52MM X 16MM