Is this for an ISSPRO pyrometer? We use a sealed Delphi/Packard connector on some of our models, so it may be different in that respect. Otherwise they are all generally interchangeable if they are Type K. However, the cheaper ones are made with solid thermocouple wire, while ours are made with stranded wire (which in turn makes them much more resistant to wire cracking due to vibrations).
What is the application? That will also tell us what length you need, as well as if you need a high temp unit. Regular temp ones use basic stainless steel, while high temp units use an Inconel stainless.