Help with Locating the Fuel Filter

[splat55]

Hey Guys,
I've attempted to use the search function to help with answering my question, but get such a wide variety of topics, that I thought I'd ask here.
I've got a '99 K3500 Crew Dually, OBS. I am going to install new injectors that I got from " the injector connection"......good people to work with by the way. Anyway, they suggest that I replace the fuel filter before installing the new injectors. I'm really an old carb guy...so this is a first for me. They also told me that they weren't talking about a fuel filter in the tank, but an inline filter. I've looked really quick under the truck, maybe missed it, but can anyone tell me where the inline filter is generally located on these truck? Any help would be appreciated. Thanks.
Brian