the base oil and ep additives are going to be the same between the two grades, or at least not be different enough to be of any significance. the only difference is the thickener consistency, the nlgi #3 is just a harder grease and will be more apt to stay in place for a given application. but like the old saying, any grease is better than no grease at all. give #2 a try, just don't be surprised if you get a lot of leakage or it pushes out the area of lubrication and it goes dry faster than usual- i'm not familiar with demolition hammers so i really can't tell you what to expect. but the fact that all that's specified is lithium based grease says it doesn't need anything special. if you decide to go buy grease for the hammer, having to go with a #2 grease because of lack of availability of #3, you might want to try aluminum complex grease. it might be more apt to stay in place over a #2 lithium which i think tends to be more fluid.
