Ahrens - Fox Model P-4:
There were only 23 Ahrens-Fox Model 'P' fire engines manufactured by the Ahrens Fox Company. Of the 23, only 9 had the distinction of being P-4 Models.

- 1921 Serial No.724 Madison, NJ
- 1922 Serial No.727 Nashville, TN
- 1923 Serial No.728 Syracuse, NY
- 1923 Serial No.729 Passaic, NJ
- 1925 Serial No.733 Passaic, NJ
- 1926 Serial No.737 Passaic, NJ
- 1926 Serial No.738 Passaic, NJ
- 1926 Serial No.739 Elkins Park, PA
- 1928 Serial No.748 Passaic, NJ
(Above: 1 of the 3 'P-4' Models in existence, Originally used by the Syracuse, NY Fire Department, and now owned by the S.P.A.A.M.F.A.A. (the Society for the Preservation & Appreciation of Antique Motor Fire Apparatus in America).
The Ahrens-Fox Fire Engine Company built 1,546 pieces of motorized fire equipment, of those, 940 were piston pumpers. The last piston pumper built was delievered to Tarrytown, New York (HT3488), Approximately 325 piston pumpers still exist today. In 1922, the rounded hood and radiator used since 1913 were replaced by a new gable hood and radiator.