Do the '54-'57 261s have the large holes for the oil-filter lines; or, are the larger holes only on the '58-'62 261s (that had full-flow oil filtration systems)?

For more information on 261s, check out Jim Carter's technical article on "The Forgotten 261 Six Cylinder" (it's not forgotten on this forum).

http://www.oldchevytrucks.com/cgi-bin/htmlos.cgi/001097.2.5428224320315357751

Tim