the picture showing "shims" on box .... never seen any such in half dozen boxes I've had apart from different years, nor any reference to them in literature - the 2 halves of the box are well machined to fit together tightly without any gasket, those pieces would slip about and easily jam the forks .... regardless of the crack you found, leave those things off, clean the grunge out and re-grease it [no oil], make sure it's all adjusted properly, and see if it doesn't work fine .... I suspect someone made those pieces to "fix" what they thought was a problem .... also, the crack could be repaired [JB Weld maybe] and shouldn't affect anything, you don't need to replace the box
Bill
