Fan, 5 Blade. PART NO: A-70240973. New 5 blade fan has a 17.5" diameter, 1.063" pilot hole, and mounting holes on 1.25" center. This fan fits multiple Allis-Chalmers Tractors. Dim A (1)17.500" Diameter Dim B (2)1.063" Pilot Hole Dim C (3)Mounting Holes On 1.250" Centers. . MODELS: Allis-Chalmers TRACTOR: D17 (Gas & Dsl.) Allis-Chalmers TRACTOR: D19 (Gas & Dsl.) Allis-Chalmers TRACTOR: WC Allis-Chalmers TRACTOR: WD45 (Gas & Dsl.) Allis-Chalmers TRACTOR: WF Allis-Chalmers TRACTOR: 170 (Gas) Allis-Chalmers TRACTOR: 175 (Gas).