Thanks for the welcome fellas, I'm from near Omaha, NE. I'll try to make this short and to the point. Both my burnt F and my F-2 are variable drive to the countershaft. I've got 23.1's on the F-2, that's why I had to pull the left drive tire to get room to get the whole sheave ass'y with sprockets off. Believe me, I wouldn't have done that if I didn't have to. On the F I have 18.4's and there was enough room to work. In the fall of 1999 I had already mounted the old orange corn head and noticed that the corn head drive sprocket on the left side had 25 teeth (I counted them today) and the right side had 13 teeth like the F had on both sides, so I changed just the left ass'y. I remember thinking at the time that maybe the black corn heads had just one drive chain, now I see they have two, also. I don't have a clue as to if the previous owner was driving his corn head with two different size sprockets or not. I am going to drive the combine over to get the head tomorrow, but looked at it today. It is a 438A Serial n7160, and the two driven sprockets on it are a 35 tooth and a 30 or 31 tooth. looks like they always drove the 35 tooth. Now, do I put back on my original ass'y with the 25 tooth corn head sprocket (and 13 tooth platform sprocket)IJ And, do I buy a 25 tooth sprocket for the right side, also. And yes, I do intend to get a manual for the black corn head, but was thinking I could pick one up on e-Bay or one of the literature dealers, etc. I get a manual for everything I own, and a parts book if possible. And, back to my original question, are there any weak or trouble spots on this head that I need to check out before I go to use it next fall. Thanks for your patience. Jim