PART NO.  SPL.PAGE  DESCRIPTION                                                           
88G257    16.A.9    Plug -drain -(oil reservoir, engine, 1600)
88G257    16.A.30   Plug -drain -(oil reservoir, engine, 1622) -part no. changed, was
    2F4249 and 2A380
2F4249X   aftermarket  Plug - drain - oil reservoir -magnetic

Drain plug for Austin B-series engines, 1953-1980 (except Twin Cam).
The magnetic plug is an aftermarket accessory, not an original factory issue part number.
Part number was changed from 2F4249 to 2A380 then 88G257.
Thread size is 3/4-14-AFT (Admiralty Fine Thread). This is a Whitworth thread form with 55-degree thread angle, 0.747" major diameter.
Use with 6K638 Washer for plug (3/4" copper crush washer).