Need a bit of help..

Fitting a ka endura gearbox into My series 2 to go down the hydraulic route..

Stripped the gearbox to fit a series 2 lsd.. Ground the crown wheel from the ka box to fit the rs turbo lsd.. New bearings fitted.. But now when building the gearbox up and tightening the casing down the diff locks up due to being too big.. Anyone had any issues like this? I've checked for a shim behind the diff hoping to put a smaller shim in but there isn't one fitted..

Help!!