I think I've figured out the brackets or flanges. A factory A/C car has a radiator with double flanges. My shroud apparently mounts to the second set of flanges, not directly to the radiator core support. The first flanges on the radiator are used to bolt the radiator to the radiator core support.
Please correct me if I am wrong.
I appreciate your answers. My thought on the big block was in regard to the depth of the Impala engine bay and the fact that a big block is longer than a small block. Due to the extra size of a big block (at least on a Camaro) a shorter shroud had to be used. I would think an Impala would have a relatively longer shroud for a small block. The shroud must be deep enough to reach from the core support to the tip of the fan blade. With a small block, that's and extra few inches. (right or wrong, that was my reasoning)
Anyway, now I'm thinking this is for a factory A/C car. I still don't know the exact year.
Do 64 and earlier cars share a common fan shroud fit? (post#2)
Is your 61 a factory a/c car? (post #3)
Reading on this site under heating and cooling, I found a post that stated a 61 to 63 Impala radiator bolted to the core support with three bolts per side. A 64 used 6 bolts per side. My shroud has three bolts per side. Maybe this is a clue. Does anyone know the width of the mounting bolts holes on a 61-63? I'll measure my shroud and see if we have a match.
Any other comments are appreciated. Thanks for our help.
Last edited by ChrisM; 02-04-2010 at 03:46 AM.
Reason: Edited to clarrify terms and add an aditional question.