I personally run a electric fan on my 48 GMC w/a 350. I use a Lincoln 2 speed fan. It pulls around 2500 cfm on low & around 4500 on high speed. I use a 40 amp relay for low & a 80 amp on high. It is w/out a doubt the best fan for the money. I paid $25.00 for mine.

Do a search & you will find tons of info on this baby.

Don