There are three different shrouds for the '60-'62 trucks.
The early one looks like the same-year Impala shrouds: a 55-gallon drum section, mounted with a pair of flanges that wrap around the side of the radiator and bolt on using the same bolts that fasten the radiator to the core. It doesn't cover the entire radiator, just the area the "drum" section covers.
The second is beefier, and fully covers the radiator. It's got a big opening that transitions to the rectangular radiator dimensions, with flanges that wrap around the sides and attach to the core like the other version.
For automatic-equipped 1/2-ton trucks, and trucks equipped with heavy duty cooling (a 3/4-ton radiator), a full face shroud was again used, fully covering the wider radiator, with mounting flanges wrapped around the side as before. I believe the auto trans radiator is the same as the 3/4-ton rad, with a trans cooler added like modern vehicles.
The 1/2-ton flange can't be used on the wider 3/4-ton radiator. Ask me how I know!
The 3/4-ton radiators will bold right in to the 1/2-ton core support, with no modifications.
They show up on ebay with some regularity, but not too many times per year.
My '62 uses a new 3/4-ton radiator (from US radiator, I believe), a reproduction 17.5-inch 7-blade clutch fan from a later muscle car, and a clutch. It's all a bolt-in deal for my 350 crate engine. In Atlanta heat, I don't have any problems unless I'm idling for a long while, and I don't have the shroud in place at this time.
The fan sits a good 8 inches back from the radiator, and even without a shroud, the big fan draws enough to pull a sheet of paper tight to the radiator from the other side.
I also have a 160-degree thermostat installed, to open the flow of water sooner-I believe that gives me some more time in heavy traffic before things get too hot.
-Brad
