One left over nut after LLY CP3 change

[Homesteader]

I've got one 10mm threaded 17mm white flanged nut left and I'm stumped as to where it goes. Coolant Y removed, no intake removal. All gold colored bracket nuts in place. Any ideas out there? Thanks!

[Homesteader]

Nut dimension is 15mm not 17mm.

[Kennedy]

Not sure if you were down as deep as the fan hub bracket?

[Homesteader]

"Helpful" neighbor removed the nut from the back of the PS pump on my son's lly which wasn't required. Couldn't let it go out the shop without finding it. Truck runs like a champ, starts easy and has no leaks. The pump had fallen apart (6m bolts backed completely out) and was sucking air, so no apparent debris downline.
Thanks for the input Kennedy, BTW the lift pump and filter kit you sent worked out beautifully for my 03.