I picked up an early 39 M over the weekend and the tractor has no serial number tag nor has it ever been drilled for one. We cleaned the clutch housing up really good with a wire brush on a grinder and there are positively no holes drilled for one. The number on the block is 807 and it is also stamped 807 on the top of the right hand frame rail just behind the grill. I have never been around an early 39 before. Are all the early M and H tractors this way? Before any one asks yes it has all "I" casting numbers, F14 style oil level petcocks, and the early round pto with the curved lever. Thank You for your help.