i can't find the part number of my cooling fan temp switch on my 305 4bbl. vin G the only number on it is dr562 2256 but i can' t find the manufacturer to get a new one do you know who made this and where i can get a new one pep boys told me it was a knock sensor but the chilton and the antifreeze that came out of the hole after i took it out disagree i think

 

Was it in the cyl. head b/w the two rear most spark plugs? If it was there than its the fan switch.

 

Jeff,

The detonation sensor is threaded into the cooling jacket as well, but along the lower edge of the case casting, not in the head.

Just a hint: The "DR" in the part number you quoted is likely "Delco-Remy". Before they were known as "AC-Delco" and now "Delphi Automotive" they were called "Delco-Remy" for about 70 years.

If the sensor you removed is about 1-3/4" in diameter and has a rounded outer edge, it is probably the detonation (knock) sensor. If it is about 1" in diameter and has a modified 12-point perimeter and one wire, it is probably a temperature sensor.

You can get an aftermarket sensor in either case, and most parts houses should have a cross reference that lists the part you need.