Originally Posted by Diamond-x
Anyone done this? I've read about and wonder if the air pocket is there for a reason. Is it a true 5 gallon addition? Any gotcha's?
Yes .. I almost did this .. but when I read about it .. the reason there is extra room in the tank is because when the temp of the gas changes the actual fluid and fumes both expand. The extra room is to support this expansion. If you re-vent the tank this can be a safe mod, but IMO it was not worth it. I thought about getting a 15 gallon fuel cell with a pump, just to refill my stock tank, if I needed to carry more gas.
GO jeep has a good write up on this
All is you do is put an "j" shaped tube on the fill hole inside the tank .. the mod cost $2 and does make room for more gas however.