In my 74 K5 sits a 350, hooked up to a th350, then to a Np205 which turns a 14 bolt FF with 3.73 gears on 35's. Now when I drive around the street it runs very cool. When I wheel it (driving slowly w/engine working hard) it overheats like a bitch. It has the big 4 core radiator with a Permacool 16" elec fan used as a puller. The fan has no shroud as it is a shroudless design. Now my theory is that there isnt enough air coming through the radiator to cool it down like there is when I'm driving at speed on the streets. What would you all recommend? I could put the stock fan setup back on w/shroud and use the permacool elec as a pusher for extra cfm's. Or I could build a shrould for the permacool...I have already replaced the thermostat, water pump, hoses, etc.. The radiator is brand new.