TF trucks 3/4 ton and larger with sixes had a heavy duty cooling option that included a larger radiator, a fan shroud and a 20" five blade fan with eccentric blades. I think it might have been stock on some of the larger trucks, but I am not sure.

The heavy radiators are about 1/2" thicker and 2" wider, but fit into the same mounting holes on the core support as the regular radiator. If you look at a standard radiator on a TF pickup, the mounting brackets on the sides are angled at about 45 degrees to fit the mounting holes on the core support. The ones on the heavy duty radiator are not angled to accommodate the wider core and tanks. The heavy duty radiator also has mounting clips for the fan shroud. The larger radiator was not offered on 1/2 ton trucks, but it does fit. US Radiator makes replacements either with standard size tubes or smaller tubes for even greater capacity. They are available with or without a transmission oil cooler.

The fan shrouds for the sixes are very hard to find, kinda like hen's teeth. Repops and originals can be found for the V8's, but not the sixes.

The five blade fans are hard to find, but they are out there. I have found two or three over the years when searching boneyards. All of the ones that I have found have been on big trucks. I have never found one on a pickup.

Here are a couple pictures of the five blade fan and shroud installed in my '57 3600 with a 261. As Bartamos pointed out, note that the exposed tips of the fan blades are key to making the shroud work.

http://s844.photobucket.com/user/ma...4868_zps1d3zlhee.jpg.html?sort=3&o=1

Here's a few pictures of the heavy duty cooling option with the five blade fan, shroud and larger radiator in a '57 6400 cement truck with a 261. That's the engine, fan and shroud that are now in my '57 3600 pictured in the above link.

http://s844.photobucket.com/user/ma...1172_zps8qvgngj2.jpg.html?sort=3&o=5

Matt