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Or a 3/4" sensor with a single spade (coolant switch) found by spark plugs in the head
Coolant switch
https://corvetteparts.com/item/sender-ecm-temperature-coolant-fan-1981-1984
That position on a '84 I'd think a cooling fan switch originally. See 8A-16 Fig 8A-10
Original part number would have been GM# 3040674 that has a somewhat unique connector originally. A connector to match that switch would be a GM# 12102621 and eBay should ID both for you with images. That fan switch does also use the same connector as a knock sensor BUT if the putty looking stuff is at the cylinder head it's a fan switch.
That position on a '84 I'd think a cooling fan switch originally. See 8A-16 Fig 8A-10
Original part number would have been GM# 3040674 that has a somewhat unique connector originally. A connector to match that switch would be a GM# 12102621 and eBay should ID both for you with images. That fan switch does also use the same connector as a knock sensor BUT if the putty looking stuff is at the cylinder head it's a fan switch.
Good call I remembered it being a little odd in 84
Your link is for an 'incorrect' part! That's NOT a fan switch. OP needs I'm quite sure a 'FAN SWITCH'. Only he knows after checking but if he's got the '84 FSM he can confirm using the FSM references I mentioned and eBay images using the part #'s I mentioned.
Yours is for the ECM temperature sensor and the OP should be able to confirm it's location using FSM 6E2-73, Fig 76
*** Knock Sensor for an '84 in the FSM should be 6E2-90, Fig 99 & 6E2-91 Fig 100
‘84 … what is this sensor please
