There are two kinds of balanced.
One is a normal assembly balance that usually uses small thin plates of steel welded to the outer perimeter of the converter.
The other is an engine balance weight that it usually about 1/4 inch thick and welded to the engine side of the converter.
Those can be cut off to produce a neutral balanced converter.
If you have a converter for a 318 it is very likely a neutral balanced and can be used with the flex plate of the 5.9 as the 5.9 flex plate has the balancing weights that the engine requires welded to it.
