Did I screw up already?

[Low84]

So I'm planning out the fuel system for my 78 c10, and I'm thinking I may have already screwed up.

I have an '04 lq4 with the electric throttle body, which i want to swap out for a cable driven one. So I picked up a 99-02 ecm and ordered a harness for that computer... Didn't the 99-02 have a return style fuel system and the 03+ have a returnless style? Am I going to have to swap out fuel rails too?!
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