[TR] TR4 wiring ignition

[Gary O'Hagan]

List,
It's starting to get ugly.  I'm working on the wiring under the dash 
and I need help.  My original ignition switch went missing. The 
replacement switch from eBay has me confused.  The switch has Three 
terminals, one single prong and Two double prongs.  My question is: 
which wires go where?  The terminals are numbered 1(single prong),2&3, 
if that helps. Do I even have the correct switch?  My next question is 
about the voltage stabilizer, but I'll save that for later (something 
about  polarity). Thanks.
Gary O