possible trans issue

Whenever i'm around half throttle when it shifts into third gear you can feel some vibration for a second until it gets into gear. Its almost like when you drift into the breakdown lane onto those bumps in the road, except to a lesser extent. Its only noticeable every so often too. Like i've mentioned before ive had the trans rebuilt/refurbished so that it shifts "quicker". I'm not exactly sure what the guy did but i hope he didnt mess something up

Whenever i'm around half throttle when it shifts into third gear you can feel some vibration for a second until it gets into gear. Its almost like when you drift into the breakdown lane onto those bumps in the road, except to a lesser extent. Its only noticeable every so often too. Like i've mentioned before ive had the trans rebuilt/refurbished so that it shifts "quicker". I'm not exactly sure what the guy did but i hope he didnt mess something up

that could be the tranny slipping...what fluid did you/he use... ?
this may also mean the pressure is low. it is possible that this is in need of measuring..

If I remember correctly these cars had issues with the lock-up converters and sometimes changing the fluid and filter would eliminate the shudder.