Garandboy--you shouldn't have too much trouble finding spots for your fire engine--the fire trucks usually mounted them up high on the windshield pillar, near the roof, rather than at the cowl. Most firetrucks that I've seen had them there, though one did have them at the cowl.
I've been searching off-and-on for 4 years to get spot lights.
I did some horse trading and got a factory driver's side spotlight with brackets for my '62 Suburban. Then the hunt was on for a passenger side. The driver's side is rare: the passenger side is extremely rare. I ended up finding a pair of NOS brackets for $160, and though that was stiff, I was happy to get them. Found a nice factory spotlight on Ebay last month, without brackets, for $72 shipped.
I don't have the passenger side spot mounted yet, but I'm looking forward to getting it on the truck.
After wanting them for four years, I ended up with a matched set in under two months!
I found out that the OE brackets for the GM Accessory spots are part numbers 141RH/LH for the exterior (right hand or left hand), and 8205RH/LH for the interior.
Unity also offered an aftermarket bracket that was sold by NAPA, Western Auto, etc.. Those brackets do not look the same at all--they're almost tear-drop shaped, and have a rather clumsy clamp for the light's shaft. I was also told they have a very slightly different mounting location from the factory spots. Those are Bracket Number 31RH/LH. I don't know what they did for the interior brackets, but have a note in to the guy I got mine from.
-Brad
