No problem.  Good luck with the repair. :)

Considering the location, it's likely the wheel cylinders. Once you've got
dead wheel cylinders, the brake shoes will also have to be replaced, no
matter how much material is remaining (because the brake fluid soaks into
them and ruins their ability to exert any braking). Also, on an old car,
once you start to remove the old wheel cylinders, it's likely the brake
lines going into them will snap (rust & rot).

If you've got a shop you trust (and you wouldn't want your brakes worked on
by one you don't), have them look over all the other brake lines while
they're working on the car. If the rear brakes are so badly shot, it's
possible that other brake lines could be very close to going south. (Brake
lines die both from external rust & rot (what with running along the bottom
of the car and being exposed to water, road salt, etc.) and internal rot
(since brake fluid is hygroscopic and, over time, can absorb enough water to
rot internal brake components). Oh, and not just the metal lines -- The
flexible brake lines should be checked for cracking and other age-related
decay of the rubber...

If they fix only the rear brakes, have them drain the *entire* brake system
and put all new fluid in. The old fluid has likely absorbed enough moisture
over time that you don't want to give any other brake component any excuse
for ruining your day...