Hi Lee,
Samely, It is nearly impossible or too expensive to find these gearboxes in Turkey.
My bug is 74 model and it has no temperature sensors. Later models were produced without them. I think and observe that 1300 ccs were mostly sold to Turkey and they all have 4375 gearboxes.
As you indicated, 4375 ratio is faster in take off and has more fuel consumption. However it may also because of the slightly more RPM than the manual bugs.