The 8hp Briggs engines had a 3/4" threaded muffler port, while the 9hp engines on up have 1" muffler ports, except OHV models which do not have internal threads. The Briggs 21**** series engines will replace an L-Head Briggs even if the tank is behind the seat. If you buy an OHV engine to replace a L-Head engine you will need to buy a muffler and remove the back right post for the muffler to fit on there. BS-Muffler-38 is the same as Snapper part number 7074453 that fits perfectly and exhaust out the side and you can still use your bagger. The throttle linkage on the new Briggs OHV engines run horizontally instead of vertically, you may have to get a longer cable for this to work correctly.
