If it comes to replacement i would go with OEM. I have found that units like Hayden tend to be a **** shoot. Some will be right on out of the box, others will not engage until boil over. They just dont spend the needed time for exact calibration. Meets some temp range specification, throw it into the box and ship it.
Higher cost for OEM is probably time spent for exact temerature calibration for the application needed.
I have recalibrated several aftermarket clutches by repositioning the spring in it's slot, after which they worked perfectly. However it was time consuming and by lucky guess trial and error.
