Interestingly enough, I was able to procure one from RockAuto in Illinois. Their part number was 779-601 and was listed to fit a 68 Chevy Nomad 230 L6 with automatic transmission. Turns out to be a GP Sorenson choke thermostat which they appear not to manufacture any longer. If anyone is interested, their wholesaler is closing out the inventory and has only 1 left. It installs perfectly and seems to function properly as well.