Coolant temperature sending unit for gauge package. Need one with 3/8" npt threads

[gnvair]

I swapped over to after market heads that use 3/8" npt threads rather than the 1/2" npt that my stock heads had. Does anyone know the part number of a sending unit with 3/8 npt threads that would be compatible with the stock coolant temperature gauge? I really want to keep the sending unit in the head and not move it it. Thanks!

 

[pagrunt]

2134793 for the current AC Delco unit, TS76 for Standard Motor Products. Search any '80 up A/G with a Chevy engine & you'll be good.

 

[79 USA 1]

This is on Rock Auto.

More Information for STANDARD MOTOR PRODUCTS TS76T

 

[gnvair]

2134793 for the current AC Delco unit, TS76 for Standard Motor Products. Search any '80 up A/G with a Chevy engine & you'll be good.

Thanks for the info!

 

[200kss]

I had bad luck with an aftermarket one of those. Had a brand new one read incorrectly and go to 225 degrees before then thermostat even opened. Swapped in a used original and its back to normal. Anyone used the new AC Delco version?

 

[gnvair]

I'm sitting here testing resistance on the different coolant temperature sending units. I have found that the GM specified part# is 8993146/D1885 for the 80-up cars with the gauge package. I have found that at 70 degrees that the resistance shows 3,160 ohms.
By comparison, the original 1/2" thread GM sender from my 78 shows about 800 ohms at the same temperature. I have another identical GM sender that shows the same (about 800 ohms).
I tested another new GM sending unit with 3/8" thread part# 25037346 and it shows about the same as the first 3/8" thread sensor mentioned above. It makes me wonder if GM did something different on the 80-up gauges to coincide with the different resistance ranges of the gauges. The issue I am having is that with the aftermarket TS76 sending unit the gauge barely moves off the cold mark. It worked perfectly before swapping the cylinder heads (and smaller sending unit).