I got these heads on a 1946 bike I bought. The heads are original 1948 dual carb modified by the man George Smith himself. Unfortunately someone down the road tried to modify these to run them on a knuck lower/cylinders. To do this they welded up the pushrod holes and remachined them to match knucklehead tappet geometry. Then they drilled and added external oilers, plugged the one pan cylinder hole and re drilled a new hole to bolt on to knuck cylindres. They plugged the internal oiler passages, and welded up the dome to get rid of the step that is used on pan cylinders to go on the smooth top knuck cylinders. I spent the last month welding up and undoing all this to make them nice back to panhead dual carb heads and fixed all the broken fins. It was a challenge but I am super happy with the finished product and this was my last test to make sure I have my cast aluminum welding down..now I will be offering my TIG welding repair services to anyone in need..let me know if you have any old motorcycle stuff that needs repair.