Did you ever find this part? These sheave halves had some wear issues that used to mean that they were scrap iron but now can be repaired. If the large snap ring at the outer end of the inner sheave won't stay in place because the groove in the sheave is worn out there is a way to fix this issue that costs about $100 at the place that fixed mine. The inner sheave was also easily broken if someone got a bit tough with it trying to pry it off of the engine crankshaft or used a jaw type puller to try and pull it loose. If you still have your old one and it's not broken or cracked let me know and I might be able to help you get it fixed.