Wrong MarkVIII Fan - Now what?

[68Formula]

So I had picked up a MarkVIII fan out of the local yard some time ago (I think it was a 1998), along with a Volvo relay setup. Finally got around to install it (ordered a new BMW sensor that operates at two temperatures).

It only seemed to operate on high when I temporarily connected it. Come to find out, i have the "single speed" version. It has the white harness connection, and the inspection cover. Removed the inspection cover to see the middle was just a dummy wire.

My understanding is the factory system is pulse width modulated by the ECM to vary the speed. I'm not running an ECU. So should I just hook up the fan to run on the low end of the BMW sensor temperature? Is there a pwm controller that I should run instead of the Volvo relay/BMW combo?

I also found this: https://www.summitracing.com/parts/f...yABEgIrbPD_BwE which looks to be an earlier model application, so it may be a two speed motor, but I can't be sure. I also have no idea if they are any good.

My hope was to do this on the cheap. I'm not too electrical savvy, so please type slow. :-)