I doubt if it will attach to the Offy intake without an adapter. That is one reason why I changed from the original canister to a spin-on (my 261 also has the Offy/Fenton combination).

[img]http://ares.cs.siena.edu/~lederman/truck/Photos/Pickup/OilFilter3.jpg[/img]

[img]http://ares.cs.siena.edu/~lederman/truck/Photos/Pickup/OilFilter2.jpg[/img]

[img]http://ares.cs.siena.edu/~lederman/truck/Photos/Pickup/OilFilter1.jpg[/img]

Tim
1954Advance-Design.com
1954 3106 Carryall Suburban
1954 3104 5-window pickup w/Hydra-Matic
The 216 and early 235 engines are not "splash oilers" -- this is a splash oiler.