Heat riser bushing gone.

The bushing for the heat riser shaft is missing @ the back of the 225 ehaust manifold causing a bad exhaust leak.

Since this is a very low milage engine, (37,000 miles) the exhaust manifold is in otherwise excellent shape. The bolts that connect the intake to the exhaust manifold are even in great shape & a bit of soaking W/Kroil has them broke free, even the 1 that goes through the center.

I could not find any manifolds locally that were in nearly as good shape so far. I want to try to replace the bushing. I have a manifold I got off of an old Hobart welder. (they used those little engines on everthging didn't they) The manifold is in poor condition but the heat riser is in good shape including the bushing. I plan to disect that heat riser to do a feasability study.

Has anyone replaced one of those bushings? Are there replacements available or will I have to make 1?