Good looking gauges!!
Not today, but yesterday. I've suspected frozen calipers for a long time, but havne't taken a first hand look.
Bottom left piston. F**king frozen.
So then, I'm a huge fan of using OEM parts, but no doubt it will cost a fortune not to mention many say EVEN NEW calipers WILL eventually fail. I've had bad luck with aftermarket, so .............even so, I'm looking at upgrading to 5thgen calipers (rockauto). Might swap out the rear calipers too. They look very "crusty" so pretty sure they might be killed.
Will be reading this thread for a while:
http://www.toyota-4runner.org/4th-gen-t4rs/196236-5th-gen-calipers.html