BW35 Auto transmission.

[PGAHOWELLS@domain.elided]

Hi all
Further study on my high speed downshift problem is pointing me at the
governer.
I have a very early box, and the ROM states there are two types of governer.
Was my autobox rebuilt with the wrong type of governer I wonder?
Does anyone know
a) Are they generally interchangeable?
b) Does anyone know the part number for the early one? My catalogue only gives
607448.
    I assume that must be the late one.
c) Could the wrong governer send the wrong pressure to the 2/3 shift valve at
3750 revs which is when I get my problem, not under acceleration, but as I
relax the pedal a bit?

I will crack it one day, but I am looking for the low cost solution if it
exists.

Peter H