Back in the late 70s and early 80s we used lots of Mobil Special grease; it was okay but nothing super special. It didn’t have a whole lot of moly in it but it was okay for general purpose use in light to medium duty applications. What it wasn’t good for was staying around very long; it was rather on the thin side and not all that tacky. As of about two or so years ago I still ran across Mobil Special but I can’t find it on their site anymore.
If you want something close to it and easy to find Valvoline has a couple of greases that are close to it, as do most other lubricant companies.
If you want to step up a notch look for a 5% moly synthetic such as Cat Dessert Gold. Again most lube companies have grease such as this but the Dessert Gold is easy to find by the tube at Cat dealers.
That said, there is some controversy about using moly grease for U-Joints, I do it with great results but others may argue non moly grease such as Chevron Delo or Ultra-Duty, of Mobil Delvac would be a better choice.
I have used a lot of the Chevron Ultra-Duty grease as it is what we switched to from Mobil Special. It’s tacky and stays put, Chevron Black Pearl would be a good cross from Mobil Special but none of these are going to be as easy to find as Valvoline grease from NAPA for example or Shell grease from Wal-Mart.