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The Evo diff is unlike any other E36 diff and as such will only fit the M3 Evo. The Evo is the only E36 to use a typ210 diff compared to the typ188 used by most other 6-pots.
If you really want to fit an Evo diff to an E36 you'll also need the Evo diff carrier, drive shafts and rear hubs AFAIK. It's a big job too and you'll need to drop the entire rear end to do the swap.
The Evo diff is 3.23:1 whereas your 325 diff (assuming it's a manual) will be 3.15:1.
Forget the Evo diff and go for the 3.0 M3 diff (LSD 3.15:1) - it is an almost straight swap....you just need to swap the input + output flanges for your 325 ones. After that it'll bolt right up