I just recently installed one of these fans in on my 70 Skylark w/a 455, so I thought I'd share. I bought the fan from a local yard in Wichita, and it fit like a glove; I fastened it using the type of fasteners that come with a transmission cooler. There are a couple inches on each side of the radiator that aren't covered though. I ordered a controller built specifically for this fan from Delta Current Control (http://dccontrol.com/). I ordered the "2sp" model, the least expensive of the bunch. It utilizes both speeds of the fan and lessens the 100A spike on the high speed by switching to high after low speed already has it spooled up (33A or so continuous). The higher end models use the high speed only, but variates the fan speed based on temp. The controller turns on low speed at 180 degrees and high speed at 190 degrees, but the temps are adjustable +/- 30 degrees via a set screw on the unit. It uses a wire lead you thread through the radiator. I don't necessarily like the sensor and I wouldn't trust it, so I wired the A/C input wire to a switch under the dash, which flips on low speed whenever I want it. After driving around town, my temp hasn't gotten over 190 and usually averages 180-ish. The fan hasn't hit high speed yet even though I've adjusted the set screw :TU:. If you go with a controller from DCC, expect about a 4 week wait for the it to arrive. The wiring wasn't too bad; the only addition I made was wiring the power to a 40A circuit breaker before it gets to the controller.
I have one of these fans sitting in my garage next to my car and debated putting it in. Maybe I'll get everything running with the factory setup and then switch over to see how it goes.
It works well, but definitely upgrade your alternator if you haven't done so already. The stock ones just can't keep up with the fan's draw.
