Here are a few pics to help distinguish this fan (which I believe is from a 1967 327 Corvette) from the '67-68 Z/28 and L78 fan. If I hadn't run across the correct fan for a great price I would have gladly used this one on my Z.
First pic is the view you would see once the fan is installed. Hi-po fan is on the left. Not a heck of a lot of difference except the hi-po fan clutch is a bit bigger.
Second pic is taken from the radiator side of the fan. Hi-po fan is on the left.
Third pic shows the clutch diameter of the fan that's for sale:
Fourth pic shows the clutch diameter of the hi-po fan:
Fifth pic shows both fans have the 'W' stamping on the hub.
Next pic shows the 3" bolt circle diameter of the fan that's for sale:
Next pic shows the 3.25" bolt circle diameter of the hi-po fan:
