Picked up one of these the other day. Already have a regular XGK EX and multiple old style XGKs. Is the J jet the same as the regular GK jet and is the D jet just an X jet? I assume so since JP8 is mostly kerosene and well Diesel is Diesel which is what the X jet is for. But wanted to verify. Love the fact that the pump comes with a little plug for keeping stuff out of the hole where the fuel line goes, not sure why the non military ones don't have this.
@Chumango That Cascade Designs list shows they don't know squat about the pre-XGK-II model. Codes would be the same as the XGK-II not the later XGK-EX. If you want to go earlier, the G/K used single-letter coding G or K. The other thing not clear: you can always use a finer jet if the maximum power isn't an issue. Eg a K jet with gasoline works fine, just slower (cooler) than the correct G jet. I would guess that the XJ jet is pretty close to the X, and the XD jet finer again.
