Sorry, didn't take any pics of the front end of the engine during disassembly; and that was five or six years ago. My mistake. I do not know of the "service library". The mostly complete engine was out of a '23 EK. Don't know the origin of the other one. Seems very if not completely similar. The parts book, "Parts Catalog Series 23-24-25 Book 4" shows a picture on Plate No. 7 Models EK, EL Crank Shaft and Bearings. It is part no. 19802 which converts to Shaft Oil Throw ring. It is concave; made of lite steel like a large washer. No key way and fits over the larger diameter step in the crank shaft where the crank timing gear fits. I'm thinking, if it is necessary at all, that it must fit behind the crank timing gear between it and the block front main bearing cradle and cap. If so, then which way does the concave surface point. And, again there's no keyway slot in this piece. I'm afraid I have to admit that since I passed the big 70 my mind doesn't remember things like it used to. Should've taken more pics ! -Jim