6600-167, Sundance® Spas Temperature Sensor, with Box End Connectors.

Use with 6540-228 Oring (sold separately, see below in related products.)
Used on these spas.
1. 2005+ 880 Systems
2. 1997-2005 850 Systems. 400,600,600-S,750, 800 and 850 Systems.
3. 1992 Suncoast, 4/96-4/98 Suntub SV/DV Systems.
4. 1997 850 Systems
5. Replaces #6600-138 and 6600-105(not shown).

Location of Temp Sensor: The Temp Sensors are located in the filter compartment on the side. They are unscrewed from the inside of the tub and the wire is fed through a tube into the equipment compartment. Follow the wire to the PC Board. To feed the new sensor, we usually drain the tub below the hole and pull the old sensor out a couple of feet into the tub, cutting the old sensor head off, we tie on the new sensor (connector end) to the old wire and pull the wire through into the equipment compartment.
Diagnostic and Installation: The connectors on the Temp Sensor are attached to a pc board connector that is located on the PC Board (usually at the top). See these instructions for Diagnostic and Installation: http://www.spaandpoolsource.com/sundancespastemperaturesensordiagnostic.aspx 

These sensors are interchangeable with the 6600-166 except for the end connector which does not connect into the 6600-167 harness. (would have to strip wires back and wire nut together.)