I agree. You will probably find that you will had to change the end of the connector on your 79 wiring to accept the one that fits your engine.
this is for a 1987 and comes with a pigtail http://www.autozone.com/engine-management/coolant-temperature-sensor/chevrolet/r10-1-2-ton-p-u-2wd/1987/8-cylinders-h-5-0l-tbi?filterByKeyWord=engine+temperature+sensor&fromString=search
or this may be the exact one you need http://www.autozone.com/electrical-and-lighting/temperature-sensor/holley-temperature-sensor/chevrolet/c10-1-2-ton-p-u-2wd/1982/8-cylinders-l-5-7l-4bl-ohv/114273_0_0/?checkfit=true
The Packard 56 connector for the Obsolete GM Nailhead sender and the Tang sender are the exact same part.
The short answer...
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You have a 3/8 NPT sender hole. 1979 and 1980 are odd ducks. They could have either 3/8" or 1/2" Tang senders depending on what engine was installed. Hopefully the gauges are the same... They probably are.
AC Delco Part # 8993164 3/8"-18 Thread; W Gauges (Tang Connector), AIRTEX / WELLS Part # 1T1008, STANDARD MOTOR PRODUCTS Part # TS76
Looks like the sender on the end in the below picture. The Long answer...
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There are several different temp gauge senders for the 73-91 squarebodies. The earlier and later temp senders have a different Ohm range for the sender.
This is a graphic from Letric Limited that shows several open terminal senders that GM used on cars and light trucks in the 1970's... Ignore the part #s in the picture. I have the right ones listed further down.
![](http://johnnynightstick.s3.amazonaws.com/IMAGES/sw-temp20senders.jpg)
GM PN from the 79-84 parts books...
AC Delco Part # 8993106 1/2"-14 Thread; W Gauges (Tang Connector), AIRTEX / WELLS Part # 1T1049, STANDARD MOTOR PRODUCTS Part # TS71
AC Delco Part # 8993164 3/8"-18 Thread; W Gauges (Tang Connector), AIRTEX / WELLS Part # 1T1008, STANDARD MOTOR PRODUCTS Part # TS76
For those with earlier trucks...
Delco PN from the 73-78 Parts Books
AC Delco Part # 1513321
Obsolete 1/2"-14 Thread; All W Gauges (
Nail Head Connector)
The Standard Motor Products TS6, Wells 1T1053, and even AC Delco G1852 "Drop In Replacements" don't have quite the same Ohm range as the original AC Delco 1513321 sender. The gauge will read slightly high or slightly low depending on who made your sender. This may be good enough for you. You decide.
Edit: for 1973-1978 model trucks, see the thread
Correct temperature sender and connector for 1973-1978 C/K trucks.
I was installing a 6.5L Diesel with a 3/8" sender hole like the OP in a 1976 chassis. My solution was to use the 1981+ temp gauge guts with the 76 face, a painted needle, and a later model 8993164 sender.
Here's a thread on another board about the obsolete Nailhead sender.
http://67-72chevytrucks.com/vboard/s...d.php?t=587190 Letric Limited has a replacement sender that's pretty accurate above 140F.
http://www.lectriclimited.com/electrical_devices.htm The C1 & C2 Corvette guys have hashed the obsolete 1513321 sender over pretty good with graphs of the Ohms Vs Temp on OEM and aftermarket senders...
http://www.lbfun.com/warehouse/tech_...eCF-Thread.pdf