Need help on new Garrett turbo manifold

Have just received new 300Tdi Garrett turbo / manifold to replace my faulty unit. After stripping old one off with mechanic, have noticed new one is not complete. New exhaust manifold only comes with cylinder 2 + 3 part assembled, Does anyone know how to remove original exhaust manifold sections for cylinders 1 + 4, are they interferance fit? Is there a sealing washer fitted into manifold to prevent leaks? Does it require heat to remove or will this damage casting? Any info will be useful, Thanks.