Hi Noah - I've got an X-ray and I've taken one apart so we have that info. Unfortunately it's a very obsolete design that uses a large inductive pick-up coil, a bulky PWM IC, and lots of discrete components (times four as each channel has it repeated). It was probably designed at least fifteen years ago and it's just not worth copying it as there are so much easier ways of accomplishing the same thing with modern components.Exactly, that's why I was suggesting taking one apart and trying to identify the actual component, if possible. Guesswork isn't what's called for here.
FWIW, if the outer shell is aluminum, I can X-ray it if someone wants to send one up here (Pacific NW). That could potentially identify the part, or at least narrow it down.
Porsche/ZF used PWM as it has very good noise immunity and an engine bay is an inherently electrically noisy environment. On my 911 these lines run from the PDK to the TCU inside the car so it's probably a six foot run in a poor environment, PWM makes sense.
I've been emailing with jjrichar and we found a good PWM convertor IC but unfortunately it's only rated to 125 deg C (though it is specified for automotive applications). Looking to see if there's anything more ruggedized available.
Edit: Looks like I cross-posted with jjrichar. What he said!