I purchased a Standard Motor TS137 temperature sender, the one with a green wire, to fix my issue with the radiator fan not engaging. My temp gauge worked fine initially, but after replacing it, my radiator fan works but now the gauge doesn't. I see on rockauto two types of sensors, one with a green wire and one with a plug https://www.rockauto.com/info/321/21...mary__ra_p.jpg

Which one should I buy?

 

There are two temperature sensors. The single wire is for the gauge and it found on the side of the block. The second one found by the gooseneck top front of the engine it is rhe CTS. It sends a signal the computer and the computer turns on the fan. The does not run until the temperature is around 220 degrees.
The fan turns on when A B are jumpered on test connector that is used to pull codes.

 

There are two temperature sensors. The single wire is for the gauge and it found on the side of the block. The second one found by the gooseneck top front of the engine it is rhe CTS. It sends a signal the computer and the computer turns on the fan. The does not run until the temperature is around 220 degrees.
The fan turns on when A B are jumpered on test connector that is used to pull codes.

 

ACDELCO 1551107 is a two sensor sold at rock auto and other part suppliers for 1986 v6 2.8

Fan has 20 amp fuse and a relay

 

For the dash temperature gauge the sensor is in the front corner of the driver side head.

For the fan relay over-ride switch the sensor is in the passenger side head around the #5 cylinder.

For the ECM the CTS is upright on the front of the intake manifold, more towards the drivers side. But to the left of the cold start injector switch (left as in looking at the engine from the front).

The TS137 appears to be for the dash gauge, while the picture you linked looks to be a CTS for the ECM.

RBob.