I think that all of the Grizzlies that came from Portugal were on CDP
allthough the first production vehicle is photographed on US track. All the
Grizzlies I have seen have been on CDP except for Joe Gillatt's in the UK,
(now on T48 rubber chevron) and Jaques Littlefield's. Both of these vehicles
are masquerading as 'M4A1's. The differences between Grizzlies and US
production are more than just track. External and internal stowage are quite
Many of the Portuguese tanks had been retrofitted with the late vision
cupola, so this is no sign of a late tank.
Regarding modifying Pz IV track, the question of why leaps to mind, as CDP
is available and probably easier than Pz IV track.