[Elbert]

I would also advocate the use of a proper mechanical radiator fan and GM fan clutch or appropriate clutch to match your fan of choice (aftermarket fan clutches are not that well made), allthough I had a Beck Arnley ?? fan clutch on my I-6 and it worked fine.

Space limitations may require electric fans.. Dual electric fans from a V-6 Ford Contur are almost a perfect fit. A properly setup electric radiator fan (likely with dual fans) will cool pretty good. Especially when you are at low rpms, where mechanical fans do not pull that much air...ie off-road. On the GM stuff I favor the large GM OEM Fan that comes on like a 1999 Yukon, with the large GM single "nut" fan clutch....all of which runs on a single fan belt. Fan shroud is important too for cooling.

Don't screw around with the flex fans.

In the case of a TBI...I think you'll be fine with the corresponding fan & clutch off the year model truck your engine equates too...if you have no issues with the fan hitting or clearance issues.