Didn't you post this question earlier in the week? If so, you already have
responses waiting for you.

 They make remote spotlights for that - manual and electrically
aimed.  The mechanical is simplest, but requires drilling a hole in
the roof.

 I'd use a post spotlight instead, like the cops buy.  Unity Products
makes them both.  http://www.unityusa.com/  Orderable online or
through any good auto parts store.

 For fixed focus lights, they call them "Alley Lights" on police car
light-bars - a basic clear foglight you can buy at the auto parts
store will have the right beam pattern for that.  And you can get a
set of roof-rack gutter brackets and a length of 1" square tubing to
make your own mounting bar for them.

 If you have a paper route, I'd get a small amber rotary beacon or
strobe for the center of the bar, just enough to warn people that
you'll be driving slowly and making lots of stops and turns, and the
occasional driving on the wrong side of the street to toss a paper to
a house on the left...  BT, DT.

    --<< Bruce >>--

Yes, they are called flashlights.

mike