If you're talking about the PT1680, you could install a gen insert, and a gen crown.
I wouldn't spend the money on a gen dial and a gen DW won't work- it goes in the opposite direction.
As Al12 says, you could get a retention ring from jmb and install a gen crystal, but that would be another $150 or so.
A gen dial won't fit in an MBW case. It will take a gen insert and T-127.
If you go to a Yuki case, well, as vlydog says, he sent it back, so forget about gen parts, I guess. NDT and J&W are other expensive options. At some point you just buy a gen