I got fed up with not being able to find units in the 10th edition Heretic Astartes Index, so decided to make my own index.  I also disliked having to go through all the character units data cards to figure out what could be attached to a given unit, so I created a list by unit of what could attach to them (if it isn't on the list, there are no characters that can attach to it in the Index).   Thought it might be useful to other players, so I've uploaded it here.  It is a word document