No, it's a totally different part. All the Senior cleaners had the same bellows, but there were several styles for the Junior, of which the U1036 is one. And none of the juniors fits the senior.
This is for the senior:
[URL unfurl="true"]http://www.ebay.co.uk/itm/Bag-Bellows-To-Fit-HOOVERS-612-638-912-IF-BELLOWS-FITTED-/231553031297?pt=LH_DefaultDomain_3&hash=item35e9a2dc81[/URL]
