Re: Thermostat sensor locations on a 1979 351W block?
Is they're two ports on the rear of the intake, and one one the front? Might be able to get sneaky and use a bronze adapter... pick one up at your local home depot. Just be sure that if you go that route to fill your engine with coolant, to crack that loose just enough to bleed the air out or it wont work properly.
I have also seen people put them in the water drain in the side of the block. Hope it helps!