I bought an Autometer Phantom 5743/4 pyrometer on e-bay, and the npt thread ends are buggered beyond worthless. Nobody has the 1/8"npt to hydraulic-type fitting on the other end of the adapter that screws into the manifold, but I got a brass one that might work. Can brass stand the temps, or will any brand type K thermocouple work with this gauge if I get a whole new one? Thanks

 

No problem with brass.

 

If you get it hot enough to melt the brass, you have other problems...

 

I have a brass one. No problems. Before the twins I saw 1600* almost everyday.

 

Back in the day some automaker used to use brass bolts in exhaust maifolds. They don't seize or rust.