If you have an 88 duke Fiero, or any VIN R duke engine 88-92,
Rodney Dickman (who has some of the highest quality Fiero parts) now has the hard-to-find
force balancers for that engine. I actually helped him get that product by doing a little research that yielded a quality company in Taiwan making them. He made the deal to buy some from them, and now sells them for far less than what GM wanted when they still had some (they have none now).
You will have to transfer your oil pump housing from your old balancer assembly to the new one, but his come with a new gerotor gear assembly, which is the heart of the oil pump. These gear assemblies are also impossible to get from GM now.