I've been trying to install an entirely new brake system in my 1981 bj42 (canadian). I've replaced all brake lines, master cylinder, wheel cylinders, calipers, etc. But never came across any kind of promotioning valve. I'm thinking the PO may have removed it, or that it just never came with one. I would think that it should have one considering it has calipers in front and drums in the rear, but unsure. Any help would be appreciated.