737 emergency exits
I've just been on a there-and-back business trip on CSA 737s. Outbound a 737-500, and returning a 737-400. I noticed that although otherwise the cabin was superficially the same, the -400 had two emergency exists over the wing, whilst the -500 had only one. Given Boeing is well known for not implementing anything unless they've no choice, could anybody enlighten me as to the reason.
Just curious.
G