Shield Crunch (released sometime in 1992) for the Commodore 64 (or Commodore 128 in 64 mode), is a program cruncher with impressive results.  The following snippit was found along with this program:

I found this powerful (but slow) packer for the 64 on a PD disk at the local library. It is very easy to use, just report source and destination names, and jmp address and $01 initial value (memory configuration, mostly $37). I have compared this packer to others I have and it always showed superior results. If some programs do not run when packed with it try changing all $2D bytes to $AE and $2E to $AF in the decompressing routine. This often helps.