Steve did you find the part and the fix? My 94’ is having a similar issue; leaks when above 1/2 a tank. I see the seal at RockAuto - https://www.rockauto.com/en/catalog/dodge,1994,viper,8.0l+v10,1099111,fuel+&+air,fuel+tank+filler+neck+seal,11241
But thought maybe it was more the sleeve right...