Bruno, There is no "cheap" muffler that I am aware of to bolt up and fit as the orig.. Of course you know that there are the Tubis and other designs but they are not cheap. There is a Flow master muffer that has the same outlet and inlet ports as the orig. muffler but pipes have to be made to bolt up to your orig manifold pipes and then add pipes to the outlet side to come out the rear for your ext. to fit on. It ain't a "quickie" job I'm sure. Where is your muffler bad? Internally or rusting through from the outside can? You know it is a large can type and can be cut open at the top to repair a baffle or metal welded on the outside to repair a rust area.