Well, in my experience with GMC/Chevy S-series i can tell you its in one of 5 locations...
1. Under the hood by the carb (i doubt yours will be here since u dont have a carb)
2. Frame rail (most common place for ford/chevy/GMC truck fuel filters.
3. Above the fuel tank (more of a dodge thing but i have seen it with chevy)
4. Front of fuel tank (ive never seen a truck with the filter here)
5 Inside the fuel tank (pain in the ass to get at but they dont have to be changed as often)
Anyway hope this helps, if not PM or e-mail me
[email protected]
Iwork at valvoline and have access to a few books with the exact location for your particular application.