I have a canon canonette and an olympus 35rc and wanted a single flash for both as I don't use flash enough for either to warrant one a piece. I'm looking at a sunpak 383 auto. It has the bounce and swivel features that I like. It doesn't have TTL but it's own auto feature which, unless I'm misunderstanding this, means that the strength of the flash is something that the flash determines itself without input from the camera which means it can be used interchangeably on different brands of cameras. Is that right?
The 383 doesn't have TTL exposure is controlled by it's own sensor. So, yes it can be used on various cameras and provide "Auto" exposure.
The 383 offers 3 choices of apertures in its auto mode. When using in manual mode, both the Canonet and Olympus RC has the guide number mode which you could set the power ratio on the flash for a certain guide number and then set that on the camera lens as well. As you focus the aperture will automatically to the correct aperture for the focus distance.