So a little background first.99 4.3 4x4 LS 140k. I live in Phoenix Arizona where it tends to be 1 or 2 degrees cooler then the gates of hell. Last summer I replaced the radiator and a clutch fan as well as the usuals due to her running hot. 180 degree Thermostat, Hoses etc. I decided to buy the Heavy/Severe Duty Clutch fan. Everything works great cools perfect no problems till today.
The clutch Fan works so good it fatigued the lower fan shroud brackets, due to so much air movement , that they broke and you can imagine what happened next? Yes it got sucked into the fan and destroyed along with 2 blades on the fan and some fin damage on the radiator as well.
So that being said. Your local auto parts stores sells these heavy duty clutch fans and they work extremely well. Just make sure your fan shroud is able to handle it and in good working order. I will be picking pieces of the shroud out of the radiator and motor for the next couple of months.
Great Forum.

 

I can't recommend using that 180* thermostat. Your engine is designed for a 195* thermostat and if you go with a lower temperature rating, your engine may not get up to correct temperature and the gas mileage will suffer.

 

just a suggestion, if i was you i would go with an electric fan conversion.
should cost less than $150.
you will have a switch mounted in your car for it and you can have the fan running good all the time.
clutch fans put alot of wear on your engine because they are turned by the crankshaft.
switchin to e-fan will up your mpg's as well.

 

A HD fan clutch shouldn't have placed any more strain on the shroud than a standard clutch. Both lock up when needed, the HD clutch just does it sooner. I suspect there was a preexisting/undiscovered problem with the lower shroud that caused the failure.

As far as making the switch to an electric fan goes, just be careful. There aren't many electric fans that pull as much air as that mechanical fan does! In your climate, airflow == cooling.