Only the overdrive is electronic. In fact with out the electronics it will skip past fourth into fifth. It was fitted in w124s in most other markets than us. It could be easily adapted without the electronics by just adding a switch for 12vlts for manual control. The driveshaft will have to be replaced.
Also I have been working on and have a conversion for the 722.6 5 speed. That is working quite well. I am a little ways away from it being 100%. But these transmissions are readily avail. in salvage yards and do not require the driveshaft to be replaced. Which is big money. See the post that I have. on this in the performance section or pm me with contact information for more details.