I believe that only the cable is different. I placed a G4 display on my g3 logic board and G4 inverter worked fine, only cable itself was different.
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PB G4 15" 1.2ghz - Pismo G3 400 mhz - iBook G3 500 "Jukebox"
"SawSmurf" G4 500 - Quicksilver G4 Dual 1ghz modding...