The wiring diagram for your 1966 Pontiac Tempest can be obtained from most General Motors dealerships. A service manual with the wiring diagram can be found at most local libraries.
These manuals (or copies) are available on eBay most all the time.
you don't
1966 GTO
Here are the 66 wiring diagrams: http://www.hammar.dyndns.org/wiring/wiring1966.htm
I restored a 1970 Pontiac Tempest about 15 years ago. I purchased a book that contains very detailed diagrams of every aspect of the car. If you're still looking for a wiring diagram, I can try to dig out this book and find it. (There's no date on this question, so I'm not sure how long ago it was asked)
go to http://www.hammar.dyndns.org/wiring/wiring1966.htm
Be wary of the tempest in a teacup. The tempest blew our ship aground.
I know that this rear is a gm standard 10 bolt, and Pontiac used it in the 64-66 gto, tempest, and le mans.
Tossed by a tempest.
A tempest is a violent storm.
chiltons repair manual at the library for 66 chevy's.
A Midsummer Tempest was created in 1974.