Again the inside of the casing must be clean clean clean. The mating surfaces of the casing must also be clean and ready for the new gaskets.
Clean up the modulating pressure housing. Check it for wear before you put it back together.
Place a new gasket on the rear end of the centre casing and fit the modulating pressure housing in position whilst making sure that the new gasket is suitably aligned; so that when you come to fit the tail cone section you're not going to have any trouble pushing the mounting bolts through.
Fit the seals for the static brake band stays and if you haven't done so already the seal for gear selector input shaft...
...and the seal on the B2 piston housing.