Exactor controls/parts wanted

I’m looking for a pair of exactor controls (sender and receiver x2). They were quite commonly used in WWII. They were a type of very precise hydraulic positioner control. We used them in various aircraft including the Sunderland and Whitley. The Americans used them in the Gruuman Avenger but manufactured them under a different design in the US which is a pity as there are quite a few of these around!

As usual any parts in any condition considered – thanks in advance.