Epic thread dig i know... BUT i read this thread recently and then went about actually getting it done!
Here is the long awaited modern replacement to the oscillator box for the 240Z rally clock. The clock has exactly the same movement as the stock setup.
This circuit completely replaces your old oscillator box and is driven by a super accurate microprocessor, instead of a tuning fork. We have a full working example after reverse engineering my own rally clock. It now keeps time more precisely than the factory unit and will be very reliable, with no moving components. We have also located a plug that will be compatible with the OEM harness for people wanting a plug in solution.
You can see from the pictures that you can actually mount this PCB inside the clock it is so small.
If you are interested, we are happy to supply just the circuit or an installed board depending on what you want. If you want a metal box from jaycar we can do that, or post us your original oscillator box and we can convert it. Let me know what you want!
First run will be about 10 units so get in quick!
PCB cost is $99AUD each which is 1/4 of the price of the actual oscillator box which may not work!
https://youtu.be/FXkWDCBmsII
https://youtu.be/hwJEogI84pw