racer4 wrote:
Ram makes a plastic cap with a tether strap.
Their cap fits snug and overlaps the outside lip of the fuel fill neck. If water gets on or near the cap it should run off the outside of the fuel fill neck.
The aluminum caps look better. I have read of people needing a different size o-ring to make it fit better. Some ship with three o-rings. It really isn't a cap, it is a plug. If the o-ring does not fit snug, water that gets on the cap could still get into the fill neck. I know, there is a second flap in the fill neck to divert water, but I prefer to not depend on it.
Mopar 82214609 Non-Locking Gas Cap (Diesel)
I have the exact same thing thanks to MeAgain!
It is what comes on the EGO Diesel. It works great!!!