I did a lot of searches on the large Stihl mount bar conversion and found a little info. Some people mill out standard bars to fit on the large mount Stihls and get a 3/8 chain in the process. I decided to stick with the factory bars, but convert from 404 to 3/8 .063 pitch. The rim sprocket was easy. 8 tooth 3/8 almost exactly like a 7 tooth 404. I went to the Stihl site and looked for bar tip information and got very confused. I took my 25" bar to the dealer and ordered a replacement tip. I also picked up a 32 inch bar and had it shipped to me. In the large Stihl mounts there are basically narrow tip and wide tip noses. My wide tip was 12 teeth in 404 and lucky 13 teeth in 3/8. The 32 bar showed up and was narrow tip style. 10 teeth 404 11 teeth in 3/8. I picked up a bunch of RM Stihl 32 inch chain loops for $12 ea. Brand new chain that I want to try some grinds on. I like the oil holes in the chain links for better oil distribution. For the 25 bar I made up a 85 link loop as the chart calls for 84. TOO SHORT! It must be the large mount bar configuration. Back to the drawing board. Here is a pick of the two bar styles and one replacement tip. Silver,, old tip, black new tip and the narrow bar underneath. Tip conversion was real easy. There are several old posts on the subject if anyone needs details. When I get the links worked out I'll post for anyone thinking about that conversion.