Yes the pin just above the lower oil port.On the 261 in my 51, the pin is flush. On the 261 in my 37 ,the Pin is in about 1/2 an inch.Interesting.I knew nothing about the pin position 6 years ago when I built the 37 engine.The 51 has the correct cannister filter. I know its filtering.I checked the pin position when I assembled the engine. Last time I changed the oil,the filter can seal was installed wrong. Oil went everywhere when the engine started. On the 37 truck with an aftermarket adapter that uses a screw on filter,I can squeeze the hoses when the engine is off, but once running I can't squeeze the hose, can feel the oil flowing through.Don't remember about the pin when I put the engine together.The oil filter is hot after the engine is warmed up.Whatever, no worries.
