If I am not mistaken, that ring shroud number corresponds to the larger diamter 260-mm fan. I do not have my information with me but I can tell you that the smaller 245-mm waqs not as widely used and was used a great deal with the racing powerplants. If you place the fans next to each other for comparison, the difference would greatly and easily be evident since the hub sections are identical and the 245 fan blades do not extend radially as much as the 260 blades. I'll see if I can post some information later. What is required by some of these kits is to machine the outer diameter of these rings. An already weakened and possibly fractured ring will fail structurally if this is done since some of the ribbing structural details casted around the perimeter of the ring are removed and the sections are thinned as a result. If you are going this route it's ok as long as you get a good ring and try to get it NDT'd (Non-Destructive Testing) to ensure it is good. I have several rings at home, let me know if you need any measurements compared to part numbers. Good luck!:haveadrin