Conclusion at the end of the season:
The accelerator pedal no longer vibrates when accelerating from a standstill - this were apparently the drive shafts, which, according to the workshop, did not fit 100 percent. The new ones (also from the 1978 Oldsmobile Toronado, but a different version) do.
The Revcon now steers better around corners, the steering is much more precise and smoother, because of the new ball joints.
The annoying vibrations from around 90 km/h are still present at the front (no more in the back - remenber?), but in contrast to before - not as noticeable, the replacement of the engine mounts did make a difference, no question, you could definitely drive like that.
I will still have both front rims repaired by the specialist near Vienna as a last resort and then have the two front tires rebalanced. It worked with the two rear rims on the tandem.
As the boss (52 years old) of my new workshop is currently unable to work physically and is therefore overloaded with the Revcon, I took it back to my previous 68 years old mechanic, who looked after the Revcon from 2020 to 2023.
Nevertheless, in my opinion, no one else could have got the Revcon back in shape after it was lying on the ground on the left front due to the ball joint breaking.
It's difficult at the moment, the all-rounders who are against spare parts are getting older, are physically vulnerable and are gradually retiring from work. Younger people are not coming up.
This situation is definitely causing my old U.S. Car fleet to face greater and greater problems. I think my mobility concept of over 30 years will go out the window in this decade.
Well, I gave the Revcon a thorough cleaning on the outside and my old mechanic is now taking care of replacing the steering rods, adjusting the track and removing the rims.
Mario (the owner of the 1978 Revcon next to mine) will help me with the correct steering parts.