Hi Mike, welcome to the forum.
I happened to be in Rochdale library with a friend who had specific research to do. I was killing time and picked up a few books while waiting for her.
This particular book was an index of Lancashire and Cheshire Wills and gave no information about the contents of the Will. If you contact the Lancashire Record Office (LRO), quoting
'DENT James Mustyhaugh near Burnley Farmer & Stone mason Aug 1835,' they should be able to tell you if they have the will there and possibly provide you with a copy of the will for a small fee. The contact details are here
http://www.lancashire.gov.uk/education/record_office/