http://www.autoperformanceengineering.com/html/lt1_kit.htmlWalbro makes many different fuel pumps. Their latest series of pumps are called their Gen-II pumps. They are a gear pump that can push an amazing amount of fuel. The models that fit most GM vechiles are the GSS242, GSS307, and GSS340. You may have also heard of the GSS242M, GSS307M, and GSS340M pumps. They are the same pump with the inlet machined-down a few thousandths so certain filters will fit on the inlet.
For several years, folks have been stuffing those pumps into the fuel modules of LT1-powered F-body and B-body cars. They weren't a direct fit, but if you trimmed a couple ribs out of the factory module, you could get the pump to fit.
In March 2004, Walbro introduced a version of the Gen-II pump with a new inlet. The pickup was offset to one side, like many of the GM vehicles on the road. The following photo shows the OE F-body pump, the GSS340 and the new F20000169 pump.
This pump is currently only available in the high pressure 255 liter/hour version. The popular GSS340M pump has been discontinued, so the kit I call FPG003 now contains the F20000169 pump and proper installation bag-o-bits for GM applications.