It's been a long while since the oil industry self mandated friction modifier in all gear fluids. So the only way to get a gear fluids w/o modifier is to order it specifically. You cant even get m1 gear fluids w/o it already in. The industry has "determined" there was no downside for have modifier in the formula even for open diffs. I don't necessarily agree with that, but they win on that one. the benefit has been most of us never have to worry about chatter because the options are not on the shelf unless you buy off the real HD shelf as in for rigs. The bottom line the only thing a dyir needs to know if you get chatter just add anti slip and ounce at a time til it disappears because too much is bad consequence as well. So thanks for bringing that up so op knows about any possibility of chatter. It is also "possible" the formula doesn't have enough anti slip, so even if it has anti slip in the formula like they all do, it doesn't mean there is enough in there. Every once in a while someone has to add more even with it in.
I like those Valvoline bags, they copied Amsoil, pretty good you don't need a pump OP, think about it. Good oil plus bags make it easy from post above.