Once I determined what OEM muffler I needed, installation was relatively easy. I have a 1982 4hp Briggs on my Snapper tiller. There was a 90* galvanized elbow coming out of the exhaust port, with a bezel nut to lock it down. Do not remove the elbow, even though it appears that you should. If you install the muffler without the elbow the muffler will parallel the the vacuum for the carburetor and can melt the rubber couplers. Use the elbow to direct the heat away from the carburetor. Use a pipe wrench to lock down the bezel nut because the weight of the muffler, especially under vibration, can work loose and fall down on the tine belt cover and melt it. The bezel nut that comes with the muffler should also be used to lock down the muffler to the threaded intake bracket that comes with the muffler, not to replace the bezel nut for the elbow.