The outer casing is similar but its the inside plumbing that's different. There are two different versions of the interior pipework for the 300TDI, either with or without ABS. You may have to disgard the interior bits to make it fit your 200TDI air intake and take a visit to B&Q or get some hose from somewhere. Use lots of sealant to stop up any holes and dont go for too narrow a pipework as the engine needs to breathe!
Once you've done that then get cracking on the front and rear axle engine and gearbox breather pipes. Here you can get some flexible pipe from B&Q or a motor factors and some pipe joiners. Soften the Disco's exisiting pipework ends with hot water and push the joiners onto the ends which will shrink back to form a tight seal. Then route all pipes higher, I joined all mine together and took the single pipe up the snorkle.
