This picture is of the round flange jugs which I have seen on both 1905 and 1906 Model L's.  I think in 1907 they changed these to hexagonal shape flanges that bolt to the aluminum block. Note that the top engine cover on my engine is off a 1907 car, by its serial number. The 1905's had no "rib" along the outside edges which were added later by Maxwell for strength. Tom Thoburn who had a wooden framed 1905 L told me he had to have one cast because his was replaced. He had heard that the original design was weak and the bolts when tightened broke off the corner ends of the plate. He had borrowed one from another early Maxwell Model L owner to have his cast. Also note the Aluminum paint on the jugs. My 1910 Model AA engine had never been touched and the heads were aluminum painted. I created quite a stir trying to find out and had opinions that Aluminum paint didn't even exist until the 1930's. Later a fellow told me he worked in an ice skate factory and they were painted with aluminum paint in 1900.