1981 C20, Help! Need to identify a valve

[Irishtrucker]

I just purchased an 81 C20.  I had the carb rebuilt and while disconnecting I managed to break a valve that looks to be connecting on the thermostat housing.  The knuckleheads at Autozone and Pep Boys can't tell me what it is or match it.  Can someone identify it for me - and maybe a possible link for purchase?  I can't budge the nut as well.  Not sure if it's welded to the housing or just stuck.  Any ideas?  Although the picture only shows one prong, the valve actually has two prongs (I broke the other one).  Thanks in advance!!

[Shifty]

It's a ported vacuum switch.

The GM p/n# 14031351, Delco is 212-268

Good luck!

[bd]

The thermal vacuum switch (TVS) threads into the thermostat housing.  It's common for them to become stubbornly tight from galvanic corrosion, especially if the antifreeze wasn't replaced periodically.  Try soaking around the threads for several days with PB Blaster and then use a six point 1/2" drive socket to break it free.  Worst case, the threads will shred and you'll need to replace the water outlet, too.  Install the new TVS using a couple wraps of Teflon tape and a high quality Teflon paste sealer.

[Irishtrucker]

Many thanks guys!!!  I'm learning as I go, so I really appreciate the help!!!