> It would easily do an indicated 140km/h on a long flat
> straight.

Was that in 4th or 5th gear?  Often top speed is reached in 4th, since the
engine can't rev to it's power peak in 5th.

>> Transmission is 4-speed manual (3+E) --
>> don't know the code.

The 3+E was a 4 speed with a 4th gear ratio similar to 5th in the 5 speed!

It worked ok on the gas engine Rabbits (except for the feeling that you
missed a gear when shifting from 3rd to 4th), but I can't imagine it
working well in a diesel.

Bill