Refer to Moss Motors part number 460-820 Adapter. This is for all MG B-series engines. This problem was reported to me, and the picture supplied by Gordie Bird of "Gordie's Garage" <mg_garage@comcast.net>.



The tubular nose on the part (at top of picture) fits into the engine block at the right rear corner of the engine to block off the back end of the main oil gallery and to conduct oil out from the cross drillind in the block to the external oil pipe going to the oil filter (or oil cooler). The hole in the block is 0.500 inch diameter (drill size). The nose on this part should be between 0.490 and 0.498 diameter. Gordie Bird says his original part (red part above) measures 0.490 diameter, and the new replacement part (silver part above) is 0.515 diameter. One of my original part measures 0.498 diameter on the nose. Anything larger than this will not fit.

Moss Motors was notified on May 13, 2004 (or earlier). Last know word is that an internal investigation has started. No other information available yet.
-----
Addendum, 7/16/04:
Per Moss Motors: All parts pulled form inventory for inspection. Some were okay, some were oversize. Oversize parts were machined down to correct size. Vendor notified. Part is now tagged for incoming inspection on all future orders. As such, this part is no longer "faulty", but can be properly installed as supplied.