The Oshkosh P-4 6x6 Truck, Airport Rescue Fire Fighting (ARFF) was equipped with a Caterpillar V6 510HP diesel engine with 1,000 gal water and 180 gallon foam tanks, and a 500 gpm pump. A variation of the P-4 called the P-4A was also procured. The U.S. Air Force bought more than 500 P-4s in the early 1970s and P-4As were purchased by both the U.S. Navy and the Australian Air Force.
The P-4 was marketed to civilian crash rescue departments as the M-1500.