I did the spal thermostat also. I had to drill and tap the Z1 adapter to the 3/8'' pipe tread. Added it in line with the upper hose. Then you need to ground the Z1 adapter case so the switch passes signal to turn on the fan at temperature. For this reason you don't use pipe tread sealant. I was able to drill and tap a hole for a small machine screw in the side of the casing. I attached a spade for small electrical connector to push on it. I don't like how this setup looks cosmetically but it does the trick. For some reason though my fan eats fuse like candy. Just got the car running again after 4.5 years so we will see. Maybe I have it fused too close to the battery and it picks up excess heat that blows it. Duno yet. I could email a pic if you like. I should have one somewhere of this setup.
