Found the "locked axle" problem to be in the emergency brake. Freed it up but cracked the rusty steel brake line going to the caliper. This car needs rear brakes but everything is very rusty. The parts-car has everything in much better condition.
Thinking about just swapping the entire rear-end. Looks like it may be easier and cheaper than going through an entire brake rebuild process.
Is there much more to it than a couple subframe mounting bolts,shocks,driveshaft,and brake lines & cables?

Thanks Ross for the ID help and links. I have a '71 280SE to fix and a '70 280S for parts. Are they as interchangeable as they look?
Thanks again,
Dan