I use an old disassembler called Donald Whisnant's Code Seeking Disassembler. https://github.com/dewhisna/m6811dis

There's a newer version out there created / modified by his daughter, Donna Whisnant's Generic Code-Seeking Disassembler with Fuzzy-Function Analyzer https://github.com/dewhisna/gendasm . I imagine this one is helpful when you have sections of code repeated from one file to another but I have never tried it.

Plenty of folks use the Tunercat disassembler. It's a good tool.