It is most likely an Answer pipe and silencer. The silencer has the gusseted mount that usually was relative to answer silencers . Tri-Z pipe ID gets sketchy unless it is a Klemm, DG, or Bassani which are more easily identified. That Answer pipe gives more mid to top end versus a DG in my experience with them, although they are very similar in shape.
Personally I would not waste time on rebuilding either shock. Yamahas were notorious for having soft shafts that pitted or got worn and a new seal head will only last a short time.
A new warrior take off, or works shock for a warrior is the best option. No matter what the archives reveal in a search, a Banshee rear shock will not work.
Here is where my long useless list of stuff nobody cares about should go...
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