what you are plugging in this modification is the channel coming from the oil pump going to the oil galley. this allows all the oil leaving the pump to go through the filter and then back into the galley to the bearings. without the plug the oil would short circuit and any filtering would be useless. i did one on the 270 in my gmc and uses a spin on filter bracket that mounts under the generator using the generator mounting bolts into the block hidden out of sight between the front crossmember and tierod for easy access. i plan on doing that on a later 235 when the time comes.
