Road King Truck Parts Locking Aluminum Vented Diesel Fuel Cap for 3 1/2" Course Thread  ASIN B074WDR7DQ
Brand: Road King Truck Parts
PLEASE MEASURE FILLER NECK BEFORE PURCHASE! Female Fitting, Vented Locking, 3 1/2" Nominal Size, 5 1/2 Threads/Inch For diesel applications only
Safety Chain and crossbar are standard Supplied with 2 matching keys (Keys not available separately)
Meets 49 CFR 393.67 requirements for vehicles built after October 1985
Across Threads - Filler Neck 3 1/2" Across Threads - Cap 3 7/16"