DADS53,

Here is a photo of the 58-63 261 oil filter assembly (the filter head/top/cap is as you describe, I think).
http://lh3.ggpht.com/-tkTLlRE_wHA/Svjv70H3yOI/AAAAAAAAABk/sVobcFpGa24/s640/IMG_4359.JPG

That is a full-flow filter - the only factory full-flow GM filter used on cars/trucks (Chev & GMC) in those years.