Posi Additive

A BTW that may make your mileage vary (YMMV): I've read that the Ford stuff stinks. I've read the Mopar stuff stinks.

The bottle of Mopar additive I just bought was not at all malodorous. Maybe it's a 'used to' sort of thing.

I've never looked forward to diff/manual trans maintenance 'cuz of the smell that just won't BeGone. Seems newer formulations of fluids have gotten around that. Although, like the old vs: new GL5 story...maybe the smell is gone 'cuz the Good Stuff is gone.

P&S: Mine's not a Sure-Grip. ...he said pretty much 'sure' of that.