🤔 what order do you have the files in the classpath? IIRC, classpath is searched in order, so the first occurrence of the class will be loaded preferentially. If the bytecode of the classes is compatible between 1.3.72 and 1.6, and the code doesn't require recompilation for the later sdk version, it is possible that just reordering the classpath might make it work? its not very nice, but it might be "good enough".