I am tearing down my engine on my 1983 300D Turbo. I'd like to replace the pistons and seals, but they are extremely expensive from the dealer. Is there somewhere else I can purchase rings and pistons for a 617.952 engine? Also who manufactures the pistons and rings? Kolbenschmidt or Mahle? I haven't sent the block, cylinder head, or the crankshaft out to the machine shop, but when I do, is there something I should know or do before handing the parts over to them? I'd appreciate any help. Thanks.