AS I understand your question, after you migrate to V6 you want all the controls in your 5.1 application to have the new 3D look and be consistent....
There is no tool that automatically goes through all your code and converts one control to another. However, depending on how you developed your code, the process might not be too bad. The key issue is the extent to which you utilized typedefs.
If you change the look of all you typedefs, the strict ones will change right away to the new look. For the regular typedefs, you'll need to have all the VIs in you application in memory at once.
Now, open the non-strict typedef and change it to the new 3D controls, and save it as a strict typedef. At this point all the instances will update. Finally reopen the typ
edef and change it back to a non-strict and save it again.
Having said all this, the process I outlined above will can take a bunch of memory (and time) depending upon how big your application is... but it will work.
As far as the nontypedef controls in your application--you're on your own...
Mike...