Google Oshkosh Fire Truck and came up with this at a Navy training website
http://www.tpub.com/content/aviation/14014/css/14014_337.htm
A top view is needed. You'll need to get more info on the running gear. Oshkosh may be able to help you - or a trip to the fire station at the local airport (ask nicely)
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Found this plus some other picts of die cast Oshkosh fire trucks while googling around. The several sites I was at said that they were sold out, but you might want to check other suppliers of diecast fire equipment to see if they have any. Check the die cast collectible stors in your area -- and check Kalmbach's sister pub regarding autos