I am looking for information regarding the average, median, or mean actual 
hourly cost(wage, benefits, insurance, taxes, etc.) to a business to employ a 
factory worker (union and non-union) in the mid-west U.S. (Detroit area) and 
other related data.

Dear Thomasm,

Thank you for your inquiry!

A list wage estimates broken down by occupation title, mean hourly and
mean annually including anything from Team Assemblers to Bindery
Workers and everything in between, can be found at:
Production Occupations
http://www.michlmi.org/LMI/wage/oes_2160.htm#b51-0000

Some examples of information at the above site includes the fact that
$16.98 is the hourly mean for a Team Assembler, $15.64 for a
Machinist, $8.55 Slaughters and Meat Packers, and there are 610
Lay-Out Workers (Metal and Plastic) whose mean annual income is
$44,260, or $21.28 an hour.

I found this free information at the Office of Labor Market
Information:
Labor Market Information
http://www.michlmi.org/index.jsp

The Michigan Electronic Library (MEL) is also a great place for any
other statistical information you might want:
MEL
http://mel.lib.mi.us/business/BU-labor.html

The Bureau of Labor Statistics Data also has Employment Cost Indexes
that you might find quite useful:
Bureau of Labor Statistics
http://data.bls.gov/cgi-bin/surveymost
or
http://www.bls.gov/ro5/home.htm#data

Also of possible interest is a table of industries with the fastest
wage and salary employment growth, 2000-2010:
http://stats.bls.gov/news.release/ecopro.t03.htm

In a recent article on auto industry jobs, Monster.com notes that:
“Some plant closings are prohibited at least until autoworkers'
contracts expire in 2003; thousands of laid-off employees are entitled
to company-paid unemployment supplements that give them 95 percent of
what they would earn if working. Moreover, in many factory
occupations, autoworkers earn significantly more than their
counterparts in other industries. In 2000, tool and die makers, for
example, earned an average of $19.76 per hour in all industries,
versus $25.76 an hour in auto plants, according to the Bureau of Labor
Statistics.
Ironically, the size the annual profit share given to each employee
may have a greater effect on total compensation than whether or not
the worker is working. The average Chrysler employee's share was
$8,100 in 2000, $375 in 2001 and will be zero this year.”
 
Article on the auto industry jobs
http://content.monster.com/autoindustry/

Also of additional use might be an article on “How Much does an
Employee Cost?” by the Massachusetts Institute of Technology’s (MIT)
Business school:
http://web.mit.edu/entforum/www/hadzima/employee_cost.htm

search terms used:
Detroit factory employment statistics
Labor statistics Detroit
Detroit employment
Average employee cost

Thank you and have a wonderful day!

Best Regards,
Skis4JC

The best overall source I've found is the Bureau of Labor Statistics. They have 
breakdowns by occupation and by Metropolitan Area. Their classification system 
would  put factory work under Production Operations

Go to web page

http://www.bls.gov/oes/   For the BLS Main Page

http://www.bls.gov/oes/2000/oes510000.htm   For Michigan Production Operations

http://www.bls.gov/oes/1999/oes_2160.htm#b51-0000   For Detroit production 
operations

I could find no Union/non-Union breakdown.