If you do decide to go with an electric fan, just install one from a Taurus; do a search and you'll find a few Taurus installations written up here on the site. Rlith has a write-up that's pretty detailed and easy to follow.
Just installed one in mine a few weeks ago, and the Taurus fan really does fit the Blazer pretty well. You'll have to buy 2 relays and an adjustable thermostat, but it's a pretty simple install.