alternator pulley

Hi all, First post so please be gentle :) Bit of brief background, I owned a w204, used, 6m old, 4k, coming up to 4 years ago. Had to sell due to change of circumstance. Been in love with Merc ever since. Fast forward to mid to late 2018, suspected epilepsy, obv couldn't drive. Last month...

Hello all, hope perhaps one of you has the expertise I need. We own a 1985 190D, however, I believe the engine has been changed to a 220 or 240. I base this on a remark I think I heard from the seller when we went to pick up the car. In any case, I have had to replace the alternator...