I was lucky today, picked up 3 lenses (all with Canon FD breechlock mounts) after seeing them in a charity shop (goodwill shop?) They all seem to be in reasonable condition as to be expected with their age. A Tamron 28mm F2.5, a Canon 135mm F2.5 SC and a Soligor Wide-Auto 28mm F2.8. The Soligor seems to have an auto aperture setting ( a green ring, see highlighted image) and possibly a removable mount with a single screw (see highlighted image of screw head). A bit of research on the net confirms that Soligor did market a removable mount but I need to know if this is one is removable. My attempt at removing the screw and trying to lift it off was unsuccessful and I am not willing to apply a lot of force to removing it. Was the T? mount made with auto aperture? I have another Soligor with a Pentax K T mount but that has 3 screws.
I looked at your photo and I don't think you would unscrew the base to change to another mount. It would be impracticable for regular use. The two photos I have uploaded are of a Tamron 85 - 210 lens that come with a bbar mount and had a M42 adapter supplied with it for use on a Minolta. To remove, depress a small leaver and twist. The Tamron is about the same era, hope this is of some help.
Thanks Craig, I'm guessing that is a Tamron adaptamatic or adaptall mount on your lens. I have answered my own question, I found a website that indicates that this lens was only made with a fixed mount.
Adaptall 2 mount that come with the lens, it's one I use for macro and closeup work. The lens goes to 1 to 3 macro. I use it with a M42 to EOS adapter on my 60D and 1D mark3.