Hi , re your box perhaps this info will help. I've just done a complete rebuild ,my layshaft was so badly worn that it had to have the shaft reground and oversize bushes . I checked the market 'cause I had a few bob ( now the box is done considerably less ) and couldn't find a new layshaft anywhere, so considered other options and having used SRM they quoted same price and talked through what they could do especially depth of case hardening weakening shaft etc. they as usual were able to put my mind at ease so off went the box ,it arrived back within 2 weeks really good job infact the best bit of the rebuild everything else turned into a nightmare even down to the new (brand new ) mainshaft which I got from Dragonfly ,it was .025 underground so bearing and inner case wouldn't bed properly and I wasted weeks getting it sorted ,even resorted to using my old shaft in the end and that sorted it . Giving Dragonfly there due once I'd sent it back they resized it and returned with new bearing FOC with apologises. so I'm now the owner of a complete box in bike and a complete box needing everything replaced,I'm goner rebuild this slowly over the next year and I will diff be using SRM again for the layshaft as I have complete trust in them. hope this helps you decide Regards Bob hebdon.