Somebody may have just taken the fan clutch out - they go bad after a not-very-long period of time. My '77 'Vette doesn't have one, instead it has a solid spacer that is about the same width as the fan clutch. It's been that way since before my dad bought it in '88. You will have a bit less overall drag on the engine with a fan clutch, but I have never noticed any problems on the 'Vette, and a '77 350 is not the highest-performance engine ever to roll out of GM. The fan shroud I don't have any idea about, but almost all GM vehicles I have seen have one. Maybe it was removed with the fan clutch?
