Fan clutch?

[Chamberpains]

This is what the back of a Keyser fan hub looks like. Those 6 small screws can come out and the clutch disc can be removed and serviced. Also when the disc gets worn, the new plates have nipples on them so they can be flipped and you can get more service life out of the clutch. This can all be done with the hub fully mounted on the truck and belts in place. They are simple to service.

Now Horton hubs are a whole other animal. My new to me truck has 1 and I learned the rebuild kit for them is close to $600, a remand hub is $750 and a full on new 1 is $1250. But they come as a whole assembly. Fan hub spindle, hub and clutch assembly as 1. I elected for the remand hub. $150 wasn't worth me finding something seriously wrong or flawed and still having to go buy a replacement. This is what the Horton fan hub looks like.