which pieces do you have from the old probe?
(probably worth reading the whole thread)
if you have the plug, you can transfer it to a new probe, but you need to know what type of thermocouple it is. if it’s a k-type, only two of those three pins have wires going to them. pick up any old k-type probe, and wire it like the old one.
you could alternatively purchase a standard thermocouple connector (see omega link up thread) and retrofit that to your mantle. @dontbanmebro posted pics once upon a time
see: Cheap mantle thermo-probe fix? - #18 by dontbanmebro
(probably worth reading the whole thread…)
if there are wires going to all three pins, then you’re looking at an RTD, probably a PT100. Omega is the gold standard for this sort of thing, but thermomart has many of the parts much cheaper.
my (geneticist style) solution for figuring out what sort of probe I’m looking at it to hook them up to a PID that will take multiple styles of thermocouple/sensor, and go through each sensor type until ice water reads 0oC and boiling water reads 100oC.
having an extra PID around for when you want to control something isn’t a bad thing.