trans leaking again after rebuild

same converter, they said it was good, not sure how they tested it. did have a tough time getting converter to settle in properly,had fluid on it though. carb base leak, maybe, no vacuum leak though. the short whistle noise is usually around 4 to 6000 rpm, maybe lasts a 10th of a second. i wiil drive some more this weekend and try to figger it out,,thanks