I agree with Retorq - if $$ is tight, buy the Jegs/Summit setup and only activate one speed of that fan. Some guys choose to activate the High speed, but under normal driving, Low is more then enough and draws less power. I personally prefer screw in temp sensors that have coolant running over them, but guys on this forum have had success sticking a prong in the radiator fins.
Also, unless you have a 140amp alternator (Chevy's HD unit for OBS Tahoes) or greater, stick with wiring in LOW speed to lessen any voltage swings.
If you have someone local that can walk you through wiring in the Volvo 2sp setup, I'd say go for it. Otherwise, it may be a tough install...(no disrespect)
However, I highly disagree on the "proven" aspect of my setup. Most guys with Tahoe's don't use this setup b/c they're comfortable with one spd, but a lot of other groups do that have multi speed fans and want to utilize both speeds idependently of their computers. It's a bit more expensive, but I'm completely automated with no toggle switches and my fan responds in two ways to increasing temperature. I also run very accurate temps b/c my temp sensors have coolant running over them right after they leave the block. (i'm not being defensive, just outlining why i did it
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