[barks944]

The first picture demonstrates the correct way to put the tensioner on as you need the big nut to put a spanner on to tension the belt as you tighten the nut on the thread.

The two tensioners are different heights if they are the same as the ones I have. The taller one is the timing belt tensioner iirc.

Edit: My dad was doing this to his 944 this evening, I went out and he's gone to bed so im not sure if he has completed doing so yet. If its still appart in the garage tommorow I will take some snaps for you.