Connecting sleeve for the installation of 50.0744.80 / 50.0745.80 on the 50.0718.00 / 50.0719.60 / 50.0719.73 / 50.0768.40 / 50.0770.60 / 50.0770.73 / 50.0816.40 / 50.0818.60 / 50.0818.73 rear muffler