A turbine section comprising: a turbine housing section including a radially inner case centered on a first axis, and a radially outer case spaced radially outwardly of said inner case, and centered on a second axis; and a plurality of tie rods including a threaded nut received on a tie rod, with said plurality of tie rods connecting said inner and outer cases (84,82), and said plurality of tie rods being spaced circumferentially about both of said first and second axes; characterised in that: said first and second axes are offset relative to each other; said plurality of tie rods extend for distinct lengths between said inner and outer cases (84,82) such that said inner and outer cases (84,82) are held at a position wherein the first and second axes are offset by a predetermined amount; a bearing for mounting a turbine rotor is mounted to a bearing mount or flange positioned within said inner case, such that a center line of the bearing will be offset from a center line of said outer case; and said threaded nuts are positioned radially outwardly of said outer case, and said tie rods include a pin head positioned radially inwardly of said inner case, with said nuts configured to be tightened on said tie rods to adjust the length of said tie rods and the distance between said inner and outer cases (84,82) to adjust the location of said first and second axes. a turbine housing section including a radially inner case centered on a first axis, and a radially outer case spaced radially outwardly of said inner case, and centered on a second axis; and a plurality of tie rods including a threaded nut received on a tie rod, with said plurality of tie rods connecting said inner and outer cases (84,82), and said plurality of tie rods being spaced circumferentially about both of said first and second axes; characterised in that: said first and second axes are offset relative to each other; said plurality of tie rods extend for distinct lengths between said inner and outer cases (84,82) such that said inner and outer cases (84,82) are held at a position wherein the first and second axes are offset by a predetermined amount; a bearing for mounting a turbine rotor is mounted to a bearing mount or flange positioned within said inner case, such that a center line of the bearing will be offset from a center line of said outer case; and said threaded nuts are positioned radially outwardly of said outer case, and said tie rods include a pin head positioned radially inwardly of said inner case, with said nuts configured to be tightened on said tie rods to adjust the length of said tie rods and the distance between said inner and outer cases (84,82) to adjust the location of said first and second axes. said first and second axes are offset relative to each other; said plurality of tie rods extend for distinct lengths between said inner and outer cases (84,82) such that said inner and outer cases (84,82) are held at a position wherein the first and second axes are offset by a predetermined amount; a bearing for mounting a turbine rotor is mounted to a bearing mount or flange positioned within said inner case, such that a center line of the bearing will be offset from a center line of said outer case; and said threaded nuts are positioned radially outwardly of said outer case, and said tie rods include a pin head positioned radially inwardly of said inner case, with said nuts configured to be tightened on said tie rods to adjust the length of said tie rods and the distance between said inner and outer cases (84,82) to adjust the location of said first and second axes.