Mazda oil pump numbers 99 through 01+
 

99~00 oil pump part #s are:

BP4W-14-100 (up through 133013)
BP5A-14-100 (133012 - 156488)
BP6D-14-100 (156488+)
ZL01-14-100 (up to 133013 with "identify mark" of ZL01 rather than BP4W).

2001 uses only BP6D-14-100

The BP4W-14-100 is substantially cheaper than the rest.