So what year did this happen in? I have an 02 with the return but am curious about when and why it changed.

 

03 with return. my friend said his 6.0 crate was from an 03 and it had returnless. Someone told me 04. 03 or 04 is the range if it helps

 

My '03 has a return.

 

My 03 has a return also. According to the radix installation manual, it was in 04 that returnless went standard, although apparently there were some "early adopters".

 

04 is the first year of the returnless system in the trucks. Earlier (but not sure exactly when) for Corvette.

 

From the service manual:

Fuel System Overview

The Fuel System is a returnless on-demand design. The fuel pressure regulator is a part of the fuel sender assembly, eliminating the need for a return pipe from the engine. A returnless fuel system reduces the internal temperature of the fuel tank by not returning hot fuel from the engine to the fuel tank. Reducing the internal temperature of the fuel tank results in lower evaporative emissions.

An electric turbine style fuel pump attaches to the fuel sender assembly inside the fuel tank. The fuel pump supplies high pressure fuel through the fuel filter and the fuel feed pipe to the fuel injection system. The fuel pump provides fuel at a higher rate of flow than is needed by the fuel injection system. The fuel pump also supplies fuel to a venturi pump located on the bottom of the fuel sender assembly. The function of the venturi pump is to fill the fuel sender assembly reservoir. The fuel pressure regulator, a part of the fuel sender assembly, maintains the correct fuel pressure to the fuel injection system. The fuel pump and sender assembly contains a reverse flow check valve. The check valve and the fuel pressure regulator maintain fuel pressure in the fuel feed pipe and the fuel rail in order to prevent long cranking times.

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Thats what I was looking for. Great info thanks!