2.38 Inch ID Freightliner M2 - Locking Fuel Cap - Chrome

Inner Diameter: 2.38" Fits Freightliner M2 Chrome Cap Assy Alum M-2 2.5"- 8 UN Triple Lead, 220 ° F Thermal Relief, 8.00" Chain & 6.50" Bail, W/ ' DIESEL FUEL ONLY' Numbers on the underside of the cap: FTA-C-13 Fuel tank MUST be vented Sold individually; image shows top and underside of cap Always make sure and if the Tank is either Vented or non-Vented in order to spec correct Vented or Non-Vented Cap. (note: a Vented Cap is made to work with a non-Vented Tank; it is also safe to use on a Diesel Fuel Tank that is already Vented) a non-Vented Tank Must have a Vented Cap to operate properly. The inside diameter (ID) of Caps used with Low-Sulfur labeled Diesel Fuel Tanks are smaller and have different treads than Caps used with Diesel Fuel Tanks that have no Low Sulfur Label.  All Caps are Threaded Female style. (except the Peterbilt Lever Style and Freightliner Cam-Cap Style) Some Older Fuel Tank fill necks (pre 2000) may have a different size and thread than current Tanks. Though Steel Tanks are not as common in the HD Truck Industry as Aluminum, it is recommended to clarify whether the tank is Aluminum or Steel.