Public Documents Masterfile has now been proxied and cataloged, at http://www.lib.umn.edu/cgi-bin/pdm.cgi . It is a good source, especially for pre-1976 documents, but a little frustrating because it is a combination of several basic resources. Some index by title, some by subject. Some provide the SuDoc number, others do not. Remember the source, especially that the Monthly Catalog data here comes ONLY from the indexes, which are by subject. And, a Monthly Catalog index entry gives you the page or entry number in the MoCat, NOT the SuDoc number of the document you are looking for.
They are moving the MoCat entries from the Beta (Working) file to the main file. In your results options, be sure to include Beta to be sure you get everything. They have inproved the Search Results screen to be more clear what you are getting: "GPO Monthly Catalog Indexes 1900-1976 with Page/Entry Numbers" and "GPO Public Documents 1789-1976 with SuDocs Numbers." Check both, plus Beta, for the most complete results.
Post comments with additional hints as you have them.
Julie