I bought a Hella one from Autodoc.
Only reason I chose it over others was that it included a new low level sensor.
Been on the car two years with no issues.
Is yours an auto or manual?
If auto then I'd suggest you get a new thermostat that sits under the bottom of the expansion tank as the old one is likely to disintegrate when you take the tank off.
If manual then I don't think it has one as it's there to control the transmission cooling.