1966 Cat D6C (76A2448) newbie question... Fan hub is loose...

Hello all,  new cat owner, new subscriber, 1st post.  Just bought the machine in subj and trucking it home tomorrow.  Grabbed the fan this morning and the hub to shaft interface was loose.  I do not believe this to be the water pump (thankfully) but rather a shaft sticking out from the accessory drive?  There are no oil leaks so my suspicion is the shaft to fan hub is suspect.  What am I looking at here?  I will need to idle it around for trailering but plan on digging in before putting it to work.  I did get a parts book and owners manual but no service manual.  Am I at least correct that this is part of the accessory drive or is this simply a bearing holder for the fan hub?  Thanks for any/all advice.  And encouragement lol.

Hi, welcome to the club. I don't have an answer for you but if you have the parts catalog for your serial #, then you'll be able to examine the relevant diagram to see what the component you're looking at is comprised of. If you post a photo of that page with the part arrowed, that might jog someone's memory

Thanks Neil. I will have it home tomorrow and be able to dig in. I believe this to be the fan hub assembly, held into bracket by one bolt. In the att'd pic the fan would be to the right, engine block to the left.. I suspect the bearings are going/gone, hopefully that is all. From the library of manuals I think this pic applies.  It looks like I'll have to pull the radiator out.  Should be lots of fun if that is the case.  It appears I have a reversible fan, don't know how common that was.  Are they trouble free in and of themselves?

Agreed, from that diagram, it appears that the pulley drives nothing but the fan. So just a pair of bearings to replace - seems straightforward but the devil's probably in the details

Well I have it home now and will post some pictures of the exact setup but for clarity I found this pic on Flea-Bay and this is the setup. So it is the water pump. Based on the s/n and this pic am I right in assuming I have a D333a? Seems like I read on here that D333c had gear driven water pump only (ie not belt driven). What I can't figure out is with the amount of play I have I don't see how it's still holding coolant. If it's the impeller shaft the seals should be long gone. Is there any history of the fan (and hub) loosening on the end of the stub shaft? The last oddity is the s/n 76A2448 tag is on the l.h.s. of the engine block. I thought a 66' in this model would have the s/n somewhere near the left rear of the frame near the driver? See att'd pic for water pump setup.  In my hard copy parts manual I come up with 1S1043 Water Pump Assembly based on my s/n.  If I can find a screen shot from the Tech Library I'll post that later as well.

For reference, the parts breakdown...