Shudder on hard acceleration from a dead stop 727.

Hey guys so i cant find much online about this but i have a 72, swinger slant 6, 727 torqueflite automatic. And sometimes when hard accelerating from a dead stop it will shudder and shake the car. Only when at a dead atop as far as i know. But if i accelerate smooth and slow it wont do it? Im confused any info would be appreciated thanks!