I took many photos to compare the classic and modern mudmans.
3 EYE DEVIL
Notice the lack of a G on the fifth button
The 8400 is thicker and feels better on the wrist
The buckle of the 8400 is rounder at the edges
The tip of the band retainer of the 8400 is shaper
The logo of the modern mudman has a new face lift. The caseback is also more well protected.