Fuel leak from filter housing
 

I have 97 3500 and I have fuel coming out of the center of the fuel filter housing on the bottom this is the second time. last time I change the filter which was about 2 months ago. All the o rings look good. Can the fuel heater cause this?

Is it coming out of the Fuel water seperator?

I guess there is open space in the center of the fuel filter canister. Someone told me that is where the water come out. But I not know

On your fuel filter there should be a plastic piece on the bottom with a spring. This piece when pressed in releases the water that has been separated from the fuel. If you don't drain that when ever you fill up water can be in there, freeze, and crack the plastic causing a leak. Your options are to replace the fuel filter with a closed bottom fuel filter ( google search will give you the answer) or you need to buy a new fuel water separator relief valve.

On the side of your fuel filter canister there is a lever, it might be yellow in color that you turn to open to drain the water out. Check and see if is closed all the way.

Get rid of it. Gano's sells the spin-on filter retrofit, well worth avoiding the many headaches of that stupid canister design.