I don't have a TTL module, so I usually use it in manual or automatic mode. My cable is just a straight PC socket type. I can actually use mine with anything from F100 to D200 (digital). I measured the sync voltage and it was something like 4 volts. Later, I confirmed with Metz tech support that it IS safe.
Be careful with yours because as far as voltages are concerned, the number in CTn matters. Some are really high voltage.
Metz tech support is pretty good. Someone will respond to your e-mail inquiry fairly quickly with complete information.
and....YES! I just picked up a 45-CT4 from an auction. It came with two leaky 45-40 NiCd packs. Today, at work (we have a battery tab spot welder), I managed to re-cell one of the packs with brandy new 2300 mAh NiMH cells.
It works wonderfully, and charges with the original charger (which is probably not what I will use long term, because, in my opinion, it's a crappy design). I'm pretty sure I can build a fast-charging drop-in charger for the 45-40 packs, using a battery charge IC, which will charge a stack of 6 NiMH cells way faster than the plug-in charger Metz sold...after all technology has progressed a bit since this design was done.
I found the appropriate (SCA-344) TTL interface cable for my F3 on eBay for $42, so I'm stoked! Working flash, repaired pack and F3 cable for under $100.