Technical What was "water pump" grease?

My old MOPAR flathead six has a grease fitting on the water pump. The factory manual specifies "water pump" grease only. Does anyone know what made "water pump" grease special, and is it still available?

 

Many websites recommend ordinary (but modern) ch***is grease, but here's some links to grease that is specifically called "water pump grease".
https://www.lubriplate.com/Online-Store/14-oz-cans/No-115-Water-Pump-Grease-14-oz-can.aspx
http://www.penriteoil.com.au/pis_pdfs/Water Pump Grease.pdf
http://www.millersoils.co.uk/automotive/tds-automotive.asp?prodsegmentID=111&sector=Cl***ics
http://www.holden.co.uk/displayProduct.asp?pcode=090.929

 

Why does it sound like something I'd make the new guy look for?

 

lubricitnusity----> I wuz gonna ask but I read the fine print. So I'll be outside lubricitnusicating my water pump now.

 

http://www.oilcenter.com/ProductInformationSheets/0-2/148.PDF