318i cracked exhaust manifold

I just bought a 1984 318i that has a cracked exhaust manifold. I found a replacement manifold for the same make and model at the local pick-n-pull that was also cracked. I also found an exhaust manifold with head pipes on a 1980 320i that will bolt up to the 318i engine but not the head pipes.

Question 1: Do all of the 318i exhaust manifolds crack?
Question 2: Should I hold out for an un-cracked 318i exhaust manifold, or adapt the 320i exhaust manifold and head pipes?

Thank You

well the crack really can happen to any car not just the 318i
its cause of the heat
ummm i say attach the 320 one on to it if it can b done cause u already have one.
if not i sugest to look around for same model one if u dont have the 320 one already