I like the manuals on CD because you can print applicable pages, Get them dirty beyond use while working on the airplane then throw away the bad page... and you still have the "original".
Here is a source that has the service manuals through 1973 and parts manuals through 1972 all on one CD. They also have the Continental engine parts and service manuals. You'll only spend a small amount on them... significantly less than any one printed manual would cost.
http://www.mccurtaintg.com/