As there was some time during the lock-down I had a look at an attitude indicator NDN6714-03, ref. no. 6370014, made by Louis Newmark, to see whether it might fit the test set....
...but after some measurements I am sure, that this indicator is remotely driven by gyro signals, but it does not match the test set as it seems to be more modern - plugs do not match and are next generation MIL plugs compared to the ones on the test set. So unfortunately the search will go on and the indicator in the Hawk even looks different:
So the following questions to the Hawk experts: In the lower middle we see the control panel of the compass reference system (red arrow). We also see the attitude indicator (blue arrow) looking different than the one I investigated. Which instruments (yellow questionmarks) are also controlled by the AHRS, probably direction indicator left one, but also the HSI?