function replaceModel()
txd = engineLoadTXD ( "supergt.txd", 506 )
engineImportTXD ( txd, 506 )
dff = engineLoadDFF ( "supergt.dff", 506 )
engineReplaceModel ( dff, 506 )
end
addEventHandler ( "onClientResourceStart", getResourceRootElement(getThisResource()), replaceModel)
Try this, it works for me