When during WW2 the VHF AM Transmitter Type 87 was introduced it came with its own 87 receiver as an option.  It wasn't a popular receiver and unlike its brother transmitter had many problems.

Their Lordships chose this Receiver, the P104 [which they called the CDU] to take the place of the 87 VHF Receiver and it worked well for some time.  However, they put this receiver 'out to grass' and in its place brought in a third receiver, the CDV/62H, of which we will hear about later.

Fitted where a VHF requirement was most relevant.

Click here CDU P104.pdf for a description, and here P104 RECEIVER.pdf for a picture.