Thruwurkin:
I've got a 52 3/4 ton with a 261.
Had a 72 with a 468 Big Block.
Ran both mechanical and electrical pusher on the 72. Summers here in Vaginny get REALLY hot and humid. I could watch the VDO temp gauge start climbing while I was in bumper to bumper traffic.
The Hotronics thermostatic switch would kick in the electric pusher fan and the change was dramatic you could watch the temp gauge drop back really quickly. I will run both on my 52 as well. When not operating the electric pusher will free wheel so even when its off and the truck is moving it moves air. I got the pusher fans for my 72 from a foreign car parts recycler it was a dual motor/dual fan unit from a wrecked Jaguar, man it would cool that 468 big block in a hurry.

Bubba