Noob alternator question

[kartoffelpanzer]

My new alternator should be arriving any day now it's the 70amp Bosch from mercedesshop.

I thought the previous (failed) alternator was an MB but it looks like it's from Kragen. Can I pull the pulleys and fan from the Kragen and install them onto the new Bosch? Maybe the pulleys and fan are MB originals, any ideas? Pic attached.

And how do I tighten everything together, it doesn't look like there's any way to grasp the shaft on the alternator. Is there some keyed feature on the shaft that fits to the fan, then I hold the fan while tightening the nut?

Lastly, is the thread on the nut RH or LH?

Thanks-
Rob
79 300SD