the 535i transmittion will bolt upto the engine ok, but the whole gearbox is about 1 inch shorter than the stock M5 unit. If you look at the gearbox off the M5 you will notice that on the pack portion on the output end there is a plate sanwiched between the two bearbox half casings. This packing plate is about 1 inch thick and is not present on a stock 535i box. This in turn causes the propshaft to be too short when trying to fit. I speak from experiance here!! i tried to fit one and ended up buying a brand new box from BMW!!! The diff ration would be wrong as well as the ratios are completely different.. Dont do it!! buy the right part, it is designed for the job!!