Although the statement Everything has a heart, and surah Ya-Sin is the heart of the Quran is properly documented, what you are asking is not. Let me try to give an answer with argument.
Coming to my argument, since Yasin is already called a heart, it doesn't have to have its own heart. But there is something called the deepest part of the heart, and by Allah, I believe the deepest part of this heart is the last two verses taken together:
36.82 Verily, His Command, when He intends a thing, is only that He says to it, "Be!" and it is!
36.83 So Glorified is He and Exalted above all that they associate with Him, and in Whose Hands is the dominion of all things, and to Him you shall be returned.
These two verses are indeed very profound in meaning, and this is the primary message of the whole Quran.
I expect my argument to be agreed upon. Jazak Allah Khair.