Need to plumb in a thermal temp switch to turn my electric fan on & off. I have no ports left in my Mopar M1 dual plane intake ('68 340). I was thinking of welding a bung into the radiator right near where the upper hose is. Do you think that would be a reliable enough spot to run the electric fans? Thanks!

That should work. Do you have an aluminum radiator? Just a guess since you mentioned welding it.

Yep, its an alumn rad from AFCO. Was gonna use a painless kit that has a switch on at 195 off at 185. The Derale kit I originally installed only lasted two summers. Had the hokey push in temp probe for the rad fins and an adjustable controller.

they make a couple of other options.
one is a bung that is in the thermostat housing.
the other would be one that you put in one of your rad hoses.

finally, it wasn't that hard to tap a new hole in the intake.

you're lucky you got two summers out of the Derale unit, We had 3 units fail within 3 months of install on customers cars. didn't matter which probe design we used. The probes themselves failed. We now are using spal units with no further problem.
And your upper tank location will be fine

Ya thats ideal! I found this one for a big block....are BB and SB not interchangeable?

https://www.meziere.com/Products/Cooling...d-BB-Mopar.aspx

If it's not too late. Get an controller with an adjustable temperature switch. With the fixed set ups, your OFF setting must be higher than your thermostat temperature. If not there will be a scenario when the fan will be blowing on a radiator that is not even flowing coolant because the thermostat is closed.