Ok i looking for this on the forum but cannot find the answer

my thermostat is stuck , but my pcm didnt trow a code , but when i cleaned my cooling system i find it because i put my thermostat to boil like 5 minutes (put it when water was actually boiling) , and it didnt open up ....... maye half of 1 milimeter, anyway so i went to the dealer , and they gave me a new one i gave my specs , durango 2001 4.7L 2wd, the problem is that when i take out again my thermostat , it was way different , is this ok?

the one on my durango is like this one (the gasket is different) , it have like a tail o valvle




and the one the dealer gave me is like this one, it soent have the tail




should i change it and put exactly the same?, or this one works too without problems?, the dealer told me it was that one , is the first thermostat i change (is actually pretty easy, taking out the coolant reservoir) my repair manual says something about that valvle should lower the flow by 50% or something like that (but my manual is for the 2000 model) , some help is apreciated please

thanks in advance