I,m not to sure about Magnum engines,but the 360LA is externally balanced were as the 318LA is internally balanced(which would use different convertors).You could search on a site like Summit Racing or Mancini,s and check for differences.
somewhere in the middle 90s...dodge changed the way they balanced the 5.9..
the weights went on to flexplate and were no longer on the converter...then the flexplate to converter went from having one offset lug to symmetrical bolt pattern...