Philip Quendstedt was a Lutheran dogmatician in the mid 17th century.  I am working on a rough English translation of this work.  For now, you can look at his treatment of the question in the original Latin over at lutheranlegacy.com.  Here is the link.  Just use the tool at the bottom of the page to go to the next page of the work.  Here is a brief English translation of Quendstedt's "state of the question":

 

The State of the Controversy

 

The question is not, whether of old and at the present time there is one way of salvation, one promise of grace, one God of the covenant, so much as the work unto justification and salvation (quantam ad justificationis & salutis negotium), and finally one faith and eternal life.  This is in all respects, as it were, certain, and greatly conforms to Sacred Scripture, which is admitted by all.  But between us and the Calvinists the controversy comes to these two : (1) Whether the Old Testament anywhere in sacred Literature (Literis) is taken for the that covenant of grace, which God made with the Fathers, Adam, Abraham, etc.  (2) Whether that covenant of grace which God made with the Fathers, is the same in substance with the New Testament.  The Calvinists affirm this, and we deny it.

 

Please note: the Calvinist position does not merely consist in the fact that the way of salvation is the same from OT to NT.  Lutherans also affirm this.  Rather, the distinctive Calvinistic position consists in the fact that the Old Testament in its entirety (including the Mosaic covenant) is essentially a covenant of grace.  The Lutherans say that the Mosaic covenant (which for them is what is properly meant by OT) is superadded to the promise given to Abraham.  It is not added to introduce a new way of salvation, but it is added as a covenant of works to convict Israel of their sin.  For more, see the quote by Anthony Burgess, available here on this site.