Just to catch up and understand the detail – the sonobuoy part is marked with

With T7725 use DIR
With T9003 use SSQ.

Both these were UK sonobuoys from the 1950/60’s

The T9003 was a Directional Passive Sonobuoy.

Thanks to Smirky we can confirm that is the top direction finder from a Mk1C sonics receiver as used on ASW Shackletons.

Much appreciated.