Manifold gasket replacement on a 2001 Buick Century. Got est of $628 w? taxes on 2001 Buick Century

Car ran hot. I was told antifreeze was leaking and the manifold gaskets need replacing. Before the car ran hot, the heat because sporadic. It would blow warm then cold. I was driving on the expressway when it ran hot. i stopped immediately. I saw no steam coming from the car.

2 answers
estimate sounds like it would be in the correct range of cost.
not a bad price according to all data.is this parts and labor and what parts are incl