I tried to remove the pipe plug on the oil galley right in front of the distributer, and stripped out the allen wrench hole. We are thinking the sending unit was maybe screwed in rear of the oil filter in the hole above the oil pressure spring and plug. Would that plug read engine oil pressure ? Has anyone used that port before? We are going to hook up a oil pressure gage temporarily to start up the engine. It would be easier to rout a wire back there than try and remove the plug. Forgot to say the engine is a flathead six. I hate to dill out the plug and use an easy out for fear of getting metal shavings in the oil galley. Dale

 

The oil pressure sender screws into a port towards the front of the engine from the distributor. Can't say about your questions on the other plugs.

 

The method I use to remove stubborn pipe plugs is to heat the plug with a torch until red, then quench it with water. The plug usually will come out easily. In your case you could drive an ease-out into the allen hole after cooling the plug.

 

You can also weld the head of a bolt into the recess of the plug. The heat of welding will loosen it, and you can put vise grips on the shank of the bolt.

 

Any threaded port that is above the level of the oil pressure sending unit will be a block coolant drain.
To drill out an oil gallery plug, use lots of grease and a left handed drill bit.

 

Got it out. I decided we'd better put the the sending unit in the proper spot. Was just about ready to pull the welder over, but decided to try mechmagcn's idea. I knocked in a screw extractor without heating it up and it just barely came out before the easy out broke. Thank's for the advice.