Hey Raul
The brake band needs to be seated on the tension adjuster and the piston rod
(much like pushrods and lifters). If this is not correct it could be the
clunking?.
You can drop the valve body to check the pin alignment.
Do you have a Manuel that show this ?(Bentley) You can use a Bentley for any
water cooled VW or Audi and get this info or I can fax you a copy if you
email me a number.
If you did not take the adj. loose there is a huge chance its not right. I
don't think I have ever bean able to get a piston in without taking it loose
and I know I have tried!

Did you happen to check the new convertor real good against the old?
If the bushing that rides on the transmission stator is wrong this could
knock as well.

Maybe I misspoke (wouldn't be the first time) about the convertor and the
governor.
I think this might only apply to transverse 010 transmissions (the governor
gear is brass and is driven by a gear in the auto half of the  trans. at a 90
degree angle and
makes it impossible to join the two halves .(this does not apply to Vernon's)
Sorry for any "additional" confusion  : )

Jeff E.   Lilburn, Ga.
87'WESTY (with a small cabinet complex) Weekender
87'GL