Recently just got two more 4560 film backs for the Hy6 cameras in from Germany - and here's something new: The 4560 film inserts are now the same size as those for the 6060 - so they are interchangeable. Have a look at the picture to see for yourself. On the left the 4560 film back and on the right my own 6060 film back.
I actually had a little heads up that this would be the case since I tried to order spare inserts for the 4560 film backs and was told they are the same as the 6060.
A lot of people ask about the 4560 film backs for the Hy6 and currently I have a few in stock.