1999 dodge ram 2500 V10 4x4 your brakes leaking fom the rear it goes from axle to frame by shock looks like a distribution valve what is it?

That sounds like your rear axle's proportioning valve. On a 1999 Dodge Ram 2500, the proportioning valve is located near the rear axle, roughly where you describe – between the axle and frame, near the shock absorber. Its job is to regulate brake pressure to the rear wheels, preventing rear-wheel lockup during hard braking. If it's leaking, it needs to be replaced.