You are absolutely correct and I apologize for the Confusion. The right side is indeed not functioning (passenger rear side) and the pix is for the problematic side.Lets clear up terminology 1st. You said "right side" works, posted a pic of rear wheel of one that doesn't, Your picture is the right side.
R/L determined by operating position, meaning you in driver seat, that's the left side looking forward. So passenger side is RH side, so your RH rear wheel doesn't work. IF I got it and not crazy.
So if driver rear (l/h side works when pedal pressed, then fluid is getting to rear, and rubber hose from chassis line to axle is ok. Correct?
But if r/h side (passenger) wheel piston not moving then need to determine if steel line from axle distribution block blocked, or is wheel cylinder frozen.
Disconnect steel line at wheel cylinder, press brake pedal. Does any fluid come out? If yes, then wheel cylinder is frozen. If not I'd disconnect same steel line at axle distribution block, press pedal, any fluid out of block?
That should get you your answer what's bad.
now when I disconnect the metal brake line going in from the axle T into the wheel cylinder and upon pressing pedal, I get a lot of fluid which indicates that the brake lines are ok. most probably it is the wheel cylinder I will order a new one and see if the problem persist.
one question is how do I know if my car was built post and pre April. apparently there are 2 versions of these cylinder and I am not sure which one I need (pre vs post April)