Camera was getting rusty so I snapped this of the model 29s I've collected:
Assuming the SNs ascend with date, they are arranged approximately chronologically from bottom to top.
What I found interesting when I compared them is how the bluing has changed over the years. It does not shows up well in the photo, but the oldest (N196XX) has a deeply reflective, almost purple look. I've seen photos of other old m29s that share this finish. The next (N149XXX) is blacker but still deeply reflective. The next (N471XXX) is about the same. The final one (BFJ7XXX) has a relatively flat black finish with little depth that looks utilitarian - almost like a m28.
I like them all. There is something solid about the heft of a model 29.
-Eric