how do I find employment records for 1940's @ Kaiser marine shipyard Sausalito CA

Dear LDS, 

I am afraid there is no answer to your question (I haven't found one
anyway, perhaps another researcher would be more successful).
According to Sandy Eskew, there are no such records (unfortunately):

"At the height of the war, women made up approximately 27% of the
100,000-strong Richmond Kaiser shipyard workforce. In other
industries, women made up to 80% of the workers. There are no
remaining employment records of all of the Kaiser shipyard employees.
We are working to create a list of women who worked at the Richmond
Kaiser Shipyards and currently have a database of over 200 names of
women who worked as welders, drafters, truck drivers, first aid nurses
and other jobs." http://sandysq.gcinet.net/richmond_kaiser_ships/kaiser11.htm

However, a woman called Amina Hassan from Ohio collects testimonies
about Kaiser shipyards, and maybe she knows more. Read about it here:
http://wwiishipyarddaycare.tripod.com/intro.htm

I searched : 
Kaiser shipyard records
<://www.google.com/search?hl=en&lr=&ie=UTF-8&oe=UTF-8&q=%22Kaiser+shipyard%22>
and also - 
"Kaiser shipyard" <://www.google.com/search?q=Kaiser+shipyard+records&hl=en&lr=&ie=UTF-8&oe=UTF-8>

Wonder if the FBI files on those employees are open to the public. 
Surely, every employee there would have been subjected to an FBI
background check.

It's quite possible to locate some of the information through The
Freedom of Information Act but it would take many months and cost far
more than $2.  Also, it would almost certainly not be very complete.