I know many people have had problems with that pesky alternator tensioner bolt ,Im here to say if you take your time while doing the job right its an easy job.Undo Battery ,pull turbo tube off with its breather tube then begin ,Two bolts must be unbolted and Two loosened,1st the top one is 17mm and has the nut formed to the assembly ,pull bolt out and set aside,2nd The center bolt ,also 17mm is the tensioner assembly which will be tightened down on install upon bolting the ALT. back onto the car,you can loosen this one with the tensioner positioning bolt which is #3 but will not need to be removed from the assembly til off the car ,the 4th is the lower assembly bolt and is by far the hardest to get to but not impossible ,open end 17 mm . Ok ,you have the alternator with the bracket off ,you start by undoing the tensioner screw till its at the end of its threads and then pry open the end piece so the nut can be taken off .This is were some garage monkeys get irritated by this assembly and dont take the time to figure the piece out.Once its disassembled you can then take your old alternator with the replacement to the parts store to have the pulley swapped over.AND DONT FORGET YOUR WIRE CLIP OFF THE OLD ALTERNATOR LOCATED AT THE BACK OF YOUR PLUG.Reassemble the tensioner bracke tto the ALT. When reassembeling I like to hang my belts on the ALT. pulley first before any bolts get put into place ,youll enjoy the slack thats there.Then start the top bolt first then the bottom but dont tighten down ,bring down the tensioner bolt till belts are tight ,then send the others home including the tensioner assembly bolt,reapply the battery and your stranded free till next time .A little side note on most aftermarket ALT. THE LIFETIME WARRENTY will definately be tested with a MB DIESEL MOTOR.