I have an older Briggs and Stratton engine (Model-171432) (Type-1123 01) (Code-9506021B) that is in need of some valve guide bushings and I could use some help in selecting the correct parts. The engine is an aluminum block with a cast iron sleeve and appears to have the sintered gray color bushing on the exhaust side and the intake side has no bushing at all. I have read several articles saying I can use a 231218 brass service bushing to repair both the intake and exhaust but I have also read either a 230655 or 261961 bushing could also be used. I understand that some of the bushings need to be finish reamed after installation and others do not so I'm wondering which bushings would best suit my application. I just want know what the right part # is for the exhaust side as well as the intake so I can get the parts ordered. I could really use some help clearing up the confusion as to which parts to use and what installation procedure entails. Thanks, Dan