Mercedes Benz repair: Transmission noise, mercedes benz 1983, loud thud

Question
My query is regarding the automatic transmission in a Mercedes Benz 1983 Model 126 (2.8 litre petrol). Each time the forward speed gear changes up or down, there is a loud thud sound, particularly so upon acceleration. The transmission assy has been rebuilt previously by a reputable garage, changed the valve body. What need to be checked to rectify the problem?

Answer
Answer:
I would check the drive shaft flex disc's, and carrier bearing.
The vehicle mounts can also cause noise = engine, transmission, differential and rear sub-frame mounts.

Driveshaft, Axle & Wheel bearing
http://www.mercedesshop.com/shopforum/showthread.php?t=142402

Transmission:
http://www.mercedesshop.com/shopforum/showthread.php?t=142395

Suspension:
http://www.mercedesshop.com/shopforum/showthread.php?t=142397

Heat shield OM617 engine mount
http://www.mercedesshop.com/shopforum/showthread.php?p=873875

Engine / motor mount DIY
http://www.mercedesshop.com/shopforum/showthread.php?p=1104023

300D engine mount blues
http://www.mercedesshop.com/shopforum/showthread.php?p=758340