Why change the design of a bearing that has worked for over 70 years, particularly on a truck that's not likely to ever get loaded to anywhere near its designed capacity? Ball bearings in good condition, lubed and adjusted properly, will outlive you, and probably a couple of more owners in the future. Change for simply the sake of change doesn't make good nonsense. Any "DB" rated wheel bearing grease will have more load bearing ability and leak resistance than what was available when the truck was new. Just don't use general purpose chassis grease- - - -it won't stay put.
Jerry

"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln
Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt!
There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway
Love your enemies and drive 'em nuts!