68 gts 340 shroud needed

67 68 and 69. In 67 the 273 Commando and Formula S cars got shrouds. Any engine with factory air got shrouds That includes slant 6.
The shroud for the slant 6 has a different number ( ends in 096 I think ) but more importantly the offset in the fan opening is opposite the V8 .
To use that shroud in a V8 application you'll have to use a much smaller diameter fan or install the shroud upside down. Yes it will fit upside down. The relief for the lower radiator hose will be on the top and the shroud will sit on the lower hose clamp.