I too was bit by the Total Crap Industries Convertor. Mine also shook like heck behind my 428 in my Mustang. I took it out and brought it to a local convertor rebuilder and he found the snout was off by .040. It too looked like was described above, with the paint worn off of only one side. He welded a new snout on and now it is as smooth as silk.
Anthony
'67 GTA Mustang 428
'66 Cobra 440 (.060 over 428)