[AlexanderB]

With various different reservoir shapes, power connectors and with/without built in speed related electronics, in almost any Citroën car from 2000 on, several Peugeot models too. Some models could have either electric or belt driven depending on what other options the car had, I don't really know if theres a whole list, but googling "Citroën electric power steering pump" will give plenty of results.

I'd say the Saxo/106 one is probably the most easiest to adapt, it has a remote mount reservoir (really just a fill cap on a hose, the pump also has internal capacity) so you can bury it somewhere down low in the engine bay, simple wiring (the wires come out with a connector that you can replace if needed), and if you get the whole thing with mounting bracket and it's little wiring loom it's even easier to make work.