They're not that hard to rebuild yourself. You can buy a rebuild kit from NAPA for under $20, not including the piston.
- Use compressed air to blow out the old piston (place a piece of wood in the caliper to let the piston slam into). Compressed air fed into the brake line hole.
- Removed the old seals
- Thereafter, I de-rusted the calipers using the electrolysis process and applied Boeshield to retain natural cast iron finish.
- Went to Harbor Freight and bought a caliper piston seal press for like $10
- Installed the new seals
- Installed the old piston as it was in good shape.
Done! The Chevy Chassis Service Manual describes the process as well.
Date Code: "87"
Note: I've already chanced the bleeder cap to the lighter pale blue.