Been ripping apart a bunch of old MPS's that are in a box. These are what I have noted in the diffences in the Brett Rebuilt units in the diaphram construction and the cover changes between early and late covers.
The problems arise in making a MPS to 2.0L calibrations with a early cover and the late diaphram as there isn't enough space or room left to get enough WOT setting.

Attached thumbnail(s)