What are you calling COBOL V3 and V4? These are not any of the standard "names". On an IBM mainframe, there are things like Enterprise COBOL and VS COBOL and others. . .
Are you actually migrating from one place to another or is this just an upgrade?
Is this (or something like it) shown on the first line of a compile output?
PP 5655-S71 IBM Enterprise COBOL for z/OS 4.1.0
Does the "old" compiler output show something like 3.x.n?
Hope this helps,