Hello: I have an Audi A6 (1996 model) that was running perfectly fine until I brought it to a repair shop to have a damaged bolt changed. Access to the bolt in question necessitated the removal of the engine from the engine bay. While the engine was out, the shop tech suggested a thorough cleaning of the engine bay and the tranny since at this time, access to these locations was quite easy. The tranny was not dis-assembled, only the outside housing was cleaned. After the bolt replacement, the engine was re-installed. Now when I put the car from P into D (drive), I can feel a heavy thud. Before the D position is the R position and as the shifter is shifted from P to R, "thud", then from R to N, N to D "thud" again. Is there anyone who has experienced this problem?