I found this today in a 71 Blazer. It mounts on the outside of the radiator support between the grille and the support on the passenger side. The white sticker on the top of the radiator suppot says the factory coolant is rated to -20 degrees F, and to maintain the level of coolant in the jug. I got the jug and bracket for $11, not bad for an item that is hard to find anymore
