We're sorry, but that engine was likely well out of production when we became the SuperTigre service center about two decades ago. We don't have any information whatsoever on the muffler bolt sizes. Likely, though, they are M2.5 with a standard thread for M2.5 bolts. We'd not know of a current muffler that would bolt right on. One of the .25-size clamp-on mufflers should work, though.