The pinion yoke on the left does not have tabs. The C-Clips that go on the U-Joint cap actually center and lock the U-Joint in place. The pinion yoke on the right with tabs is used with a outside lock regular U-Joint. The tabs center and lock the U-Joint in place.
A flange can also be a plate or ring to form a rim at the end of a pipe when fastened to the pipe (for example, a closet flange). A blind flange is a plate for covering or closing the end of a pipe. A flange joint is a connection of pipes, where the connecting pieces have flanges by which the parts are bolted together.