261's don't provide a location in the block, they expect you to tee into the external oil filter lines. The original fitting had a 1/2" npt into the block to the 1/2" flare fitting of the old lines with a 1/8" npt tap for the oil filter, on the return hose. I am running hydraulic hoses to my oil filter so I drilled and tapped a 1/8" npt hole into my oil filter housing on the outlet side of the filter. All of the oil line kits you buy at your flaps have a 1/8" npt to compression adaptor for the gauge line included in them.
