Episode 815: Its a Covenant of Old and New

Ark of the Covenant: This designation appears 40 times, 30 times in association with the Divine Name, and associates the ark with it function as the keeper of the covenant documents.

Ark of God/YHWH: The ark is mentioned 82 times in association with God (i.e. "Ark of God," "Ark of Yahweh," "Ark of the God of Israel," "Ark of the Lord of the earth," etc.), associating the ark with its other function as the base of the Mercy-seat which is the meeting place between God and His covenant people.

Ark of the Testimony: This designation also appears 40 times and associates the ark with its covenant document. This title for the ark is not found outside the books of the Pentateuch.
(Anchor Bible Dictionary, vol. I, "Ark of the Covenant" page 386-7).