If this is an M30 engine, I will let you know that there is two exhaust manifoilds on engine and I do think you can use the same both for the front and rear.... The both down pipes are also very cheap new, I payd under 20 quid for my 735iA E32 for one of the down pipe (if we are talking about the same part?)
Thanks 78dude, I'm pretty sure the two manifolds are different as the down pipe part comes off them at different angles. I'm not saying you didn't pay £20 but that seems extremly cheap for an exhaust!!