Don't bother trying- - - - -the converter has too many places for debris to hide to make any kind of draining or flushing effective. Swap your converter for a reconditioned unit. The rebuilders cut the weld, dismantle the converter, and replace/repair anything that's necessary. Most trans shops won't guarantee a rebuild unless the converter is changed out, also. The average cost is about 50 bucks exchange, so it's not a deal-breaker.
Jerry

"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln
Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt!
There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway
Love your enemies and drive 'em nuts!