PART NO.  SPL.PAGE  DESCRIPTION                                                           
6K885     15.F.3    Bearing -ball for shaft -(1st motion shaft, gearbox assy, 1500)-
    changed to 97H512 Com.(G)A1861, Fin.(G)MA8010 -changed to 6K885 Com.(G)MA8011- 
    (changed back to first number)
6K885     16.F.1    Bearing -(1st motion shaft, gearbox assy, 1600 and 1600-MK-II)
6K885     TC.F.3    Bearing -shaft front -(1st motion, gearbox, Twin Cam)
97H512    15.F.3    Ball bearing for shaft (input) -Com.(G)A1861 -Fin.(G)MA8010 -(was 
    6K885) -Changed to 6K885 Com.(G)MA8011 -(Changed back the way it was)

This is the front bearing, on the gearbox input shaft, for Austin B-series 3-synchronizer gearboxes, 1953-1967, including MG Z-Magnette, ZB-Magnette, all MGA, and MGB 1962-1967. This bearing had two different BMC part numbers (maybe more), changing from 6K885 to 97H512 and then back to 6K885 again.

Generic dimensions:
1.3750" (34.93mm) ID x 3.0000" (76.2mm) OD x 0.6875" (17.46mm) Width with External Retaining Ring groove. required.

Notice the external retaining ring has a different part number, and the ring may or may not be included with the bearing, depending on who you buy it from.
... See part number 6K886 for the separate snap ring information.

Ball Bearing, Gearbox Front
all MGA and early MGB through 1967.
127-200          Moss Motors Ltd USA
2-2001           Victoria British Ltd
6K529            BMC, British Leyland
6K885            BMC 
6K885            Brown & Gammons
B3052G           BAP GEON

Manufacturers
11132-32         NISSAN	
119G             SPORTSCAR
8110435          NASCO
LJ138G           R&M (original supplier to BMC)
LJ138N           RHP
LJ138NR          RHP
LS1212K          FAG
RLS11N           SKF
RLS11NR          STEYR