FHP Federal deck lights
 

These aren't (yet) the correct, single D1 setup, but you could always "shorten" them down by removing two of the lamps and trimming the width of the center housing down before re-imstalling the end cap. Not a bad idea if you need the Federals, cuz you CAN'T get them anywhere.

http://www.ebay.com/itm/FEDERAL-SIGN...9e3561&vxp=mtr

This particular seller seems to have just about anything Federal Signal. I picked these up earlier this year from this guy to use in my '91 FHP Unit 432 (Lo-Jack unit).

http://www.sspmustang.org/forums/att...3&d=1375299176

http://www.sspmustang.org/forums/att...4&d=1375299179

Here is an in-service pic of the car. In talking with Trooper Brown, he said he still has the hat in the picture.

http://www.specialservicemustang.net...HPfederal2.jpg