Noise behind the instrument board on my Mk9

To be more precise, it happens at take off, and thus at lower speeds. It is behind the instrument board, between the steering column and the light switch (on my LHD car).
It is a form of high tone clattering. The revcounter is electric on this 1961 car, so not the cable drive. Itnis not over to the right where the speedo is.
I have looked on the engine side of the fire wall, but when I drive, I hear it coming from the inside,
A mystery to me…:scream:
Has anyone else experienced this?

The car has the T700 4-speed box with a kit from Johnś Jaguar in TX. I have come to suspect the gear selector and its metal tube going down along the firewall and bending backward along the rear of the engine.
Will look from underneath when lifting the car next time.