Brian;
Your right, but I've seen (west coast) 'by-pass' type (low pressure 216/235) filters on the 261s.
They don't belong there, but they could have been done by some "hobby shopper".
I think that's what he might have had, as his engine is to old for the full flow type.
If the pin were 'in' and the filter removed, no oil would go th the rear bearings.
This is why they ALL are best removed unless there like the one you pictured here (factory) a while back with the solid steel lines..
