I have a detached garage that has a 3 wire feed, powered from a separate 100amp disconnect from the main panel. Originally the old box had the ground and neutrals together on the same bar. I discovered this upon installing a new box and assumed it was wired wrong due to everything I've read about sub panels and how they shouldn't be bonded.
Upon further research I have seen others say that since my sub panel isn't connected to my main panel in the house, that my sub should have ground and neutral bonded. I'm without power for 3 days now.