PRC3432 This is the part you want it goes on the right side of the steering wheel.
Go down this page to find it http://rovahfarm.com/defenderignitionpage2.htm
I wired mine into my high beams too (to activate a relay), so when I dim my lights, my off road light go off too.
While you are at it, do this to your regular running light to remove all the amperage from you head lamp light switches. You'll be amazed at how much brighter your lights will be, simple install.