Hey Mitch,
I think everything as far back as a 300 TDI disco 1 had the 24 spline rover diff.
So that would be D1 and D2 and Def 90 (front and rear) and the front of a Def 110.
The only thing I vaguely remember was that the D2s possibly had a different method of staking the pin.
As far as I know they should all be as good (or as bad!) as each other if you're just after a stop-gap.
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