Here is my attempt to compile a list of the Air Ministry equipment numbers and some notes about what they were.
WWII military aircraft equipment is mainly built in a modular fashion, so that power units, aerial connections, control panels etc. could be varied according to the detail of the installation, which itself was given an ARI number. Most of the main equipment numbers refer to either receivers or transmitters and are the main functional parts of the installation. Other modules, such as power units, were numbered using a different system, often by numeric type number. Note that some transponders seem to have been numbered like receivers possibly to confuse the enemy. ]