Product review (3 stars): Great heater, but buy an original Whirlpool high-limit cutout
The heater itself is great - works fine and is an exact fit for the original.  But after two months the high-limit thermostat cut out for no obvious reason, and once it opens it's dead. (This is the unit in the lower left of the product photo with a steel back plate, white body, and two electrical contacts sticking up.  It goes on the top of the heater chimney on the back of the dryer.)  I checked the air flow, the heater resistance, and the operation of the other two thermostats and everything was OK, so I ordered an original Whirlpool replacement from Amazon and soldered a 14 gauge wire across the terminals of the high-limit thermostat to keep the dryer going until I can get the replacement part delivered in a few days. (There are three other thermostats on the dryer, so the chance of burning my house down is nil.)  Notice that all the sellers of replacement high-limit switches show a white body, while the Whirlpool original has a black body.  My advice is that if your dryer is old enough to need a new heater, buy a whole new set of thermostats, preferably the Whirlpool brand, and keep any that still work as spares.  It is not uncommon for a thermostat to fail with no other problems in the dryer and replacement takes just a half hour if you have the part on hand.  In the years that I have had this Kenmore dryer, I have replaced thermostats maybe 4 times without any malfunction causing the thermostat failure.