To be certain, I highly recommend you:
* Consult your owner's manual: This is the best source for the precise location.
* Use a repair manual: A Haynes or Chilton manual for your specific year and model Astro will have diagrams and detailed instructions.
* Search online for your specific year, make, model, and engine: Many automotive forums and websites have pictures and discussions about fuel filter location.
Because you're working with fuel, be extremely cautious. Fuel is flammable, and you should work in a well-ventilated area, away from any open flames or sparks.