What is the procedural equivalent in California of Rule 60(b) of the
Federal Rules of Civil Procedure (motion to vacate judgment for fraud
on the court)?

Try California Code of Civil Procedure Section 473(b):

"The court may, upon any terms as may be just, relieve a party
or his or her legal representative from a judgment, dismissal, order,
or other proceeding taken against him or her through his or her
mistake, inadvertence, surprise, or excusable neglect.  Application
for this relief shall be accompanied by a copy of the answer or other
pleading proposed to be filed therein, otherwise the application
shall not be granted, and shall be made within a reasonable time, in
no case exceeding six months, after the judgment, dismissal, order,
or proceeding was taken. . . ."

http://www.leginfo.ca.gov/cgi-bin/displaycode?section=ccp&group=00001-01000&file=469-475

I note that unlike FRCP 60(b), fraud is not specifically enumerated
here as a grounds for relief.

Thanks for the guidance. I found what I need in the following:

"After six months when relief is no longer available under section 473
of the Code of Civil Procedure for mistake, inadvertence, surprise, or
excusable neglect, an otherwise valid judgment may only be set aside
for extrinsic fraud or mistake." In re Marriage of Melton, 28
Cal.App.4th 931, 33 Cal.Rptr.2d 761 (Cal.App. Dist.6 08/31/1994)."

Thank you.