Good morning, Terry;
Well, there may be only four "threads," but there are many postings. The main one runs for several pages of postings.
"Yes," to both of the questions about Tamron Lenses. They are good. Some of them performed better than the equivalent lenses from the main camera manufacturers. I think that is a fair endorsement.
Yes, the Adaptall mounts do come off. Both the earlier Adaptall and the more common later Adaptall-2 mounts come off in just about the same way. On the back of the lens coming foward from the Adaptall mount you will see two (2) rectangular tabs that go into mating recesses on the back of the Tamron Lens. Look closely; they are there. Gently lift or pry both of them out of their recess and move them slightly sideways so they will not go back and latch into the recess. Then you can rotate the Adaptall mount counter-clockwise (sort of to the left) off the bayonet mont on the back of the Tamron Lens.
End of Part One of Two Parts.