205 blocks are fitted to all 2wd cossie!how ever a rs500 205 block is different to a normal one,much stronger(dont know the ident of a 500 one tho!)200 blocks were fitted on the 4x4,although i have been told earlier 4x4 casn have a 205 block!(not sure if true or not!!) i beleive the difference between a 205(normal)and a 200 block is around the water jackets thicker wall between them and the cylinder bore depends what u want really standard 205 block good for 400bhp maybe 430!!500 205+200 good for more although they still are prone to cracking