[MrFixr55]

Depending on the frequency of the vibrator you may have to "bridge" the electrolytics with mylar or ceramic caps, as electrolytic caps are not necessarily good at filtering out high frequency noise. A standard vibrator runs at somewhere between 100 and 200 Hz. this electronic vibrator may operate at a higher frequency.

Verify that the entire metal can of the new "vibrator" is grounded.  If the can is cut for stuffing and taped, with a paper cover added, but the 2 haves of the can are not in good electrical contact, or if the shield is not physically connected to the chassis, this may cause part of the can or the entire can to act as an antenna.

Is this noise on the bench only or in the car only?  Does the noise occur only with the solid state "vibrator" and not with a standard vibrator?  Is this a single ended or Push Pull output stage?  Push pull stages should be more forgiving of common mode (i.e. power supply) noise.  However, if the noise shows up in previous stages, that is a different story.

Consider replacing the 0Z4 with a 6X5 or 12X5 depending on the car's voltage.  (Most car companies changed to 12V in 1956.)  Other than the need for connections for the heater, I believe that the pinouts are the same.  Some radios are wired to accept either tube.  Alternately, convert to silicon diodes.  The 0Z4 is a gas discharge rectifier and can contribute its own noise.

If all is good on the bench and in the car in ACC position but noisy when the car is running then determine if the noise is from the generator, alternator or ignition system.  Frequency will vary with engine RPM.  Alternator noise is a cleaner sound than generator or spark noise.