PART NO.  SPL.PAGE  DESCRIPTION                                                           
6K886     15.F.3    Spring ring for bearing -(1st motion shaft, gearbox assy, 1500)
6K886     16.F.1    Spring ring -bearing -(1st motion shaft, gearbox assy, 1600 and
    1600-MK-II)
6K886     TC.F.3    Spring ring -bearing -(1st motion, gearbox, Twin Cam)

This page is for the 6K886 "Clip", circlip, snap ring, 3-inch external retaining ring that resides on the outside diameter of the 6K885 (alternate part number 97H512) front bearing in the gearbox (for Austin B-series 3-synchronizer gearboxes).

Notice this external retaining ring has a different part number from the bearing, and the ring may or may not be included with the bearing, depending on who you buy it from.
... Alternate part no's for ring: 6K886; 326-180 (Moss Motors)
... Ring available from www.abingdonmotors.com.au (maybe)

These days most of the businesses who will sell you the bearing will list the retaining ring as NLA (No Longer Available). However, when they do sell you the bearing, this snap ring will most likely be included already installed on the bearing. So it bloody well is available, they just don't sell it separately.
So far I haven't been able to find a picture of the snap ring by itself (but maybe next time I disassemble a gearbox).

... Also see gearbox tech article GT-117A for more information.