The infamous ZF 4 HP 22 E/H automatic tansmission is another sotry. Early models had a three speed box, this became four speed and eventually had electronic control and a Sport/Economy/Manual switch next to the gear lever.
Check the fluid with the oil (Dexron II or III) warm and the engine running or you'll get a reading which can be way out. The fluid should be clear and not burnt. It must be changed every 30K or else. Failure to change the fluid means a new tranny around 150K miles so insist on proof. If it's not been changed for a long time then leave it. Changing it now will let all sorts of crud circulate back into the tranny and wreck it, this is why my own car is now a manual. There is also a filter screen under the tranny which should be changed every 60K, a good chance to check and clean the magnets in the drain pan too.
Never ever rev an auto Six at high rpm in park or neutral. This will cause over pressure on the A clutch pack and burn it out, time for a new trany. A pressure relief hole was added in the late 80's to reduce the problem.
Vibration under acceleration means it's time for a new centre bearing which isn't expensive. Other drive shaft wibrations can be caused by worn flex discs at either end. Post 82 cars had a more robust design.
From the
John G Burns Home Page
They can run between $1800 - $2400 to rebuild or replace
![Frown [:(] [:(]](/images/smilies/frown.png)