It prolly never had any liquid in it. Looks like the factory used a type of grease. Could be "Bentonite" grease, like in Peerless crashboxes.
I would use "0" moly grease, or mix your own using moly paste ( assembly lube) and "0" or "00" grease. #1 will work also.
It ain't rocket science!
'Course if yer house has more wheels than yer truck...