Speedometer dont work!

"Hello everyone. I have a question… The "speedomeeter and odometer don’t work, any idea where to look for the reason and how to fix it? Thank you in advance for any information

Have you checked the connector on the gearbox? It should be on the gearbox next to the firewall.

Check capacitors. I had to replace all on mine.

where to look for them?

Capacitors are electronic components located on the circuit boards. When I bought my 3000GT, there were several issues, all caused by bad capacitors ( tachymeter, AC display, and radio). You will need to remove the instrument cluster and check the circuit boards. Yes, there are several. I hope this is helpful to you