I've been looking at the Seiko tuna & baby tuna. They look awesome. So many choices. I'm a bit confused about one thing I thought I had read about people doing a tuna mod with older watch models that would fit in the aftermarket shrouds or something to that affect, maybe it was they were switching movements. Don't know I tried doing searches to find out about this. No luck so I thought maybe you all could fill me in on this.